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PARTICLE PHYSICS on the Eve of LHC
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Faculty of Physics of Moscow State University
INTERREGIONAL CENTRE FORADVANCEDSTUDffiS
Proceedings of the Thirteenth Lomonosov Conference on Elementary Particle Physics
PARTICLE PHYSICS on the Eve of LHC Moscow, Russia
23 - 29 August 2007
Editor
Alexander I. Studenikin Department of Theoretical Physics Moscow State University, Russia
'lit
World Scientific
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PARTICLE PHYSICS ON THE EVE OF LHC Proceedings of the 13th Lomonosov Conference on Elementary Particle Physics Copyright © 2009 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the Publisher.
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ISBN-13 978-981-283-758-5 ISBN-IO 981-283-758-2
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Moscow State University Faculty of Physics Centre for Advanced Studies
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Russian Foundation for Basic Research Russian Agency for Science and Innovation Russian Academy of Sciences Russian Agency for Atomic Energy Dmitry Zimin "Dynasty" Foundation Institutions Faculty of Physics of Moscow State :::iK()be,lts,!ln institute of Nuclear Physics, Moscow State Centre for Advanced Studies Joint Institute for Nuclear Institute for Nuclear R""'"",,,,",rr-h Theoretical and i=vY,ari,rnQlnt",1 Budker Institute of Nuclear
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International Advisory Committee
E.Akhmedov (ICTP, Trieste & Kurchatov Inst.,Moscow), S.Selayev (Kurchatov Inst.,Moscow), VSerezinsky (LNGS, Gran Sasso), S.Silenky (JINR, Dubna), J.Sleimaier (Princeton), MDanilov (ITEP, Moscow), GDiambrini-Palazzi (Univ. of Rome), ADolgov (INFN, Ferrara & ITEP, Moscow), VKadyshevsky (JINR, Dubna), S.Kapitza (EAPS, Moscow) A.Logunov (IHEP, Protvino), V.Matveev (INR, Moscow), P.Nowosad (Univ. of Sao Paulo), L.Okun (ITEP, Moscow), M.Panasyuk (SINP MSU), VRubakov (INR, Moscow), D.Shirkov (JINR, Dubna), J.Silk (Univ. of Oxford), ASissakian (JINR,Dubna), ASkrinsky (INP, Novosibirsk), ASlavnov (MSU & Steklov Math.lnst, Moscow) ASmirnov (ICTP, Trieste & INR, Moscow), P.Spiliantini (INFN, Florence), Organizing Committee
V.Sagrov (Tomsk State Univ.), VSelokurov (MSU), VSraginsky (MSU), AEgorov (ICAS, Moscow), D.Galtsov (MSU), AGrigoriev (MSU & ICAS, Moscow), P.Kashkarov (MSU), AKataev (INR, Moscow), O.Khrustalev (MSU), VMikhailin (MSU & ICAS, Moscow) AMourao (1ST/CENTRA, Lisbon), N.Narozhny (MEPHI, Moscow), A.Nikishov (Lebedev Physical Inst., Moscow), N.Nikiforova (MSU), VRitus (Lebedev Physical Inst., Moscow), Yu.Popov (MSU) , VSavrin (MSU), D.Shirkov (JINR, Dubna), Yu.Simonov (ITEP, Moscow), AStudenikin (MSU & ICAS, Moscow), V.Trukhin (MSU)
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Moscow State University Interregional Centre for Advanced Studies
SEVENTH INTERNATIONAL MEETING ON PROBLEMS OF INTELLIGENTSIA "RIGHTS and RESPONSIBILITY of the NTELLIGENTSIA" Moscow, August 29, 2007
Presidium of the Meeting VASadovnichy (MSU) - Chairman VV.Belokurov (MSU) J.Bleimaier (Princeton) G.Diambrini-Palazzi (Universiry of Rome) VG.Kadyshevsky (JINR) S.P.Kapitza (Russian Academy of Sciensies) N.S.Khrustaleva (Ministry of Education and Science, Russia) A.I.Studenikin (MSU & ICAS) - Vice Chairman V.I.Trukhin (MSU)
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FOREWORD
The 13 th Lomonosov Conference on Elementary Particle Physics was held at the Moscow State University (Moscow, Russia) on August 23-29,2007 under the Patronage of the Rector of the Moscow State University Victor Sadovnichy. The conference was organized by the Faculty of Physics and SkobeJtsyn Institute of Nuclear Physics of the Moscow State University in cooperation with the Interregional Centre for Advanced Studies and supported by the Joint Institute for Nuclear Research (Dubna), the Institute for Nuclear Research (Moscow), the Budker Institute of Nuclear Physics (Novosibirsk) and the Institute of Theoretical and Experimental Physics (Moscow). The Russian Foundation for Basic Research, the Russian Agency for Science and Innovation, the Russian Academy of Sciences, the Dmitry Zimin "Dynasty" Foundation and the Russian Agency for Atomic Energy sponsored the conference. It was more than twenty years ago when the first of the series of conferences (from 1993 called the "Lomonosov Conferences"), was held at the Department of Theoretical Physics of the Moscow State University (June 1983, Moscow). The second conference was held in Kishinev, Republic of Moldavia, USSR (May 1985). After the four years break this series was resumed on a new conceptual basis for the conference programme focus. During the preparation of the third conference (that was held in Maykop, Russia, 1989) a desire to broaden the programme to include more general issues in particle physics became apparent. During the conference of the year 1992 held in Yaroslavl it was proposed by myself and approved by numerous participants that these irregularly held meetings should be transformed into regular events under the title "Lomonosov Conferences on Elementary Particle Physics". Since then at subsequent meetings of this series a wide variety of interesting things both in theory and experiment of particle physics, field theory, astrophysics, gravitation and cosmology were included into the programmes. It was also decided to enlarge the number of institutions that would take part in preparation of future conferences. Mikhail Lomonosov (1711-1765), a brilliant Russian encyclopaedias of the era of the Russian Empress Catherine the 2nd, was world renowned for his distinguished contributions in the fields of science and art. He also helped establish the high school educational system in Russia. The Moscow State University was founded in 1755 based on his plan and initiative, and the University now bears the name of Lomonosov. The 6th Lomonosov Conference on Elementary Particle Physics (1993) and all of the subsequent conferences of this series were held at the Moscow State University on each of the odd years. Publication of the volume "Particle Physics, Gauge Fields and Astrophysics" containing articles written on the basis of presentations at the 5th and 6th Lomonosov Conferences was supported by the Accademia Nazionale dei Lincei (Rome, 1994). Proceedings of the 7th and 8th Lomonosov Conference (entitled "Problems of Fundamental Physics" and "Elementary Particle Physics") were published by the Interregional Centre for ix
x Advanced Studies (Moscow, 1997 and 1999). Proceedings of the 9th , 10th , 11th and 12th Lomonosov Conferences (entitled "Particle Physics at the Start of the New Millennium", "Frontiers of Particle Physics", "Particle Phlsics in Laboratory, Space and Universe" and "Particle Physics at the Year of 250 Anniversary of Moscow University") were published by World Scientific Publishing Co. (Singapore) in 2001,2003,2005 and 2006, correspondently. The physics programme of the 13 th Lomonosov Conference on Elementary Particle Physics (August, 2007) included review and original talks on wide range of items such as neutrino and astroparticle physics, electroweak theory, fundamental symmetries, tests of standard model and beyond, heavy quark physics, nonperturbative QCD, quantum gravity effects, physics at the future accelerators. Totally there were more than 350 participants with 113 talks including 32 plenary (30 min) talks, 48 session (25-20 min) talks and 33 brief (15 min) reports. One of the goals of the conference was to bring together scientists, both theoreticians and experimentalists, working in different fields, so that no parallel sessions were organized at the conference. The Round table discussion on "Dark Matter and Dark Energy: a Clue to Foundations of Nature" was held during the last day of the 13 th Lomonosov Conference. Following the tradition that has started in 1995, each of the Lomonosov Conferences on particle physics has been accompanied by a conference on problems of intellectuals. The 7th International Meeting on Problems of Intelligentsia held during the 13 th Lomonosov Conference (August 29, 2007) was dedicated to discussions on the issue "Rights and Responsibility of the Intelligentsia". The success of the 13 th Lomonosov Conference was due in a large part to contributions of the International Advisory Committee and Organizing Committee. On behalf of these Committees I would like to warmly thank the session chairpersons, the speakers and all of the participants of the 13 th Lomonosov Conference and the 7th International Meeting on Problems of Intelligentsia. We are grateful to the Rector of the Moscow State University, Victor Sadovnichy, the Vice Rector df the Moscow State University, Vladimir Belokurov, the Dean of the Faculty of Physics, Vladimir Trukhin, the Director of the Skobeltsyn Institute of Nuclear Physics, Mikhail Panasyuk, the Directors of the Joint Institute for Nuclear Research, Alexey Sissakian, the Director of the Institute for Nuclear Research, Victor Matveev, the Director of the Budker Institute of Nuclear Physics, Alexander Skrinsky, and the Vice Dean of the Faculty of Physics of the Moscow State University, Anatoly Kozar for the support in organizing these two conferences. Special thanks are due to Alexander Suvorinov (the Russian Agency for Science and Innovations), Gennady Kozlov (JINR) and Oleg Patarakin (the Russian Agency for Atomic Energy) for their very valuable help. I would like to thank Giorgio Chiarelli, Dmitri Denisov, Francesca Di Lodovico, Hassan Jawahery, Andrey Kataev, Cristina Lazzaroni, William C. Louis, Frank Merrit, Thomas MUller, Tatsuya Nakada, Daniel Pitzl, Jacob Schneps, Claude
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Vallee and Horst Wahl for their help in planning of the scientific programme of the meeting and inviting speakers for the topical sessions of the conference. Furthermore, I am very pleased to mention Alexander Grigoriev, the Scientific Secretary of the conference, Andrey Egorov, Mila Polyakova, Dmitry Zhuridov, Dasha Novikova, Maxim Perfilov and Katya Salobaeva for their very efficient work in preparing and running the meeting. These Proceedings were prepared for publication at the Interregional Centre for Advanced Studies with support by the Russian Foundation for Basic Research, the Russian Agency for Science and Innovations and the Russian Agency for Atomic Energy. Alexander Studenikin
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CONTENTS Thirteenth Lomonosov Conference on Elementary Particle Physics Sponsors and Committees Seventh International Meeting on Problems of Intelligentsia Presidium tィセ@
v vii セ@
Fundamentals of Particle Physics The Quantum Number of Color, Colored Quarks and Dynamic Models of Hadrons Composed of Quasifree Quarks V. Matveev, A. Tavkhelidze
3
Discovery of the Color Degree of Freedom in Particle Physics: A Personal Perspective O. W. Greenberg
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The Evolution of the Concepts of Energy, Momentum, and Mass from Newton and Lomonosov to Einstein and Feynman L. Okun
20
Physics at Accelerators and Studies in SM and Beyond Search for New Physics at LHC (CMS) N. K rasnikov
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Measuring the Higgs Boson(s) at ATLAS C. Kourkoumelis
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Beyond the Standard Model Physics Reach of the ATLAS Experiment G. Unel
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The Status of the International Linear Collider B. Foster
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Review of Results of the Electron-Proton Collider HERA V. Chekelian
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Elements from Bs Recent Results from the Tevatron on CKM m。エイセ@ Oscillations and Single Top Production, and Studies of CP Violation in Bs Decays J. P. Fernandez
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Direct Observation of the Strange b Barion L. Vertogradov xiii
st 85
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Search for New Physics in Rare B Decays at LHCb V. Egorychev
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CKM Angle Measurements at LHCb S. Barsuk
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Collider Searches for Extra Spatial Dimensions and Black Holes G. Landsberg
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Neutrino Physics Results of the MiniBooNE Neutrino Oscillation Experiment Z. Djurcic
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MINOS Results and Prospects J.P.Ochoa-Ricoux
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The New Result of the Neutrino Magnetic Moment Measurement in the GEMMA Experiment A. G. Beda, V. B. Brudanin, E. V. Demidova, V. G. Egorov, M. G. Gavrilov, M. V. Shirchenko, A. S. Starostin, Ts. Vylov
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The Baikal Neutrino Experiment: Status, Selected Physics Results, and Perspectives V. Aynutdinov, A. Avrorin, V. Balkanov, 1. Belolaptikov, N. Budnev, I. Danilchenko, G. Domogatsky, A. Doroshenko, A. Dyachok, Zh.-A. Dzhilkibaev, S. Fialkovsky, O. Gaponenko, K. Golubkov, O. Gress, T. Gress, O. Grishin, A. Klabukov, A. Klimov, A. Kochanov, K. Konischev, A. Koshechkin, V. Kulepov, L. Kuzmichev, E. Middell, S. Mikheyev, M. Milenin, R. Mirgazov, E. Osipova, G. Pan'kov, L. Pan'kov, A. Panfilov, D. Petukhov, E. Pliskovsky, P. Pokhil, V. Poleschuk, E. Popova, V. Prosin, M. Rozanov, V. Rubtzov, A. Sheifier, A. Shirokov, B. Shoibonov, Ch. Spiering, B. Tarashansky, R. Wischnewski, I. Yashin, V. Zhukov
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Neutrino Telescopes in the Deep Sea V. Flaminio
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Double Beta Decay: Present Status A. S. Barabash
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Beta-Beams C. Volpe
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T2K Experiment K. Sakashita
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xv Non-Standard Neutrino Physics Probed by Tokai-to-Kamioka-Korea Two-Detector Complex
N. Cipriano Ribeiro, T. Kajita, P. Ko, H. Minakata, S. Nakayama, H. Nunokawa
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Sterile Neutrinos: From Cosmology to the LHC
F. Vannucci
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From Cuoricino to Cuore Towards the Inverted Hierarchy Region
C. Nones
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The MARE Experiment: Calorimetric Approach to the Direct Measurement of the Neutrino Mass
E. Andreotti
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Electron Angular Correlation in Neutrinoless Double Beta Decay and New Physics
A. Ali, A. Borisov, D. Zhuridov
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Neutrino Energy Quantization in Rotating Medium
A. Grigoriev, A. Studenikin
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Neutrino Propagation in Dense Magnetized Matter
E. V. Arbuzova, A. E. Lobanov, E. M. Murchikova
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Plasma Induced Neutrino Spin Flip via the Neutrino Magnetic Moment
A. K uznetsov, N. Mikheev
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Astroparticle Physics and Cosmology International Russian-Italian Mission "RIM-PAMELA"
A. M. Galper, P. Picozza, o. Adriani, M. Ambriola, G. C. Barbarino, A. Basili, G. A. Bazilevskaja, R. Bellotti, M. Boezio, E. A. Bogomolov, L. Bonechi, M. Bongi, L. Bongiorno, V. Bonvicini, A. Bruno, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, M. P. De Pascale, G. De Rosa, V. Di Felice, D. Fedele, P. Hofverberg, L. A. Grishantseva, S. V. Koldashov, S. Y. Krutkov, A. N. Kvashnin, J. Lundquist, O. Maksumov, V. Malvezzi, L. Marcelli, W. Menn, V. V. Mikhailov, M. Minori, E. Mocchiutti, A. Morselli, S. Orsi, G. Osteria, P. Papini, M. Pearce, M. Ricci, S. B. Ricciarini, M. F. Runtso, S. Russo, M. Simon, R. Sparvoli, P. Spillantini, Y. 1. Stozhkov, E. Taddei, A. Vacchi, E. Vannuccini, G. Vasilyev, S. A. Voronov, Y. T. Yurkin, G. Zampa, N. Zampa, V. G. Zverev
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Dark Matter Searches with AMS-02 Experiment A. Malinin
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Investigating the Dark Halo R. Bernabei, P. Belli, F. Montecchia, F. Nozzoli, F. Cappella, A. Incicchitti, D. Prosperi, R. Cerulli, C. J. Dai, H. L. He, H. H. Kuang, J. M. Ma, X. D. Sheng, Z. P. Ye
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Search for Rare Processes at Gran Sasso P. Belli, R. Bernabei, R. S. Boiko, F. Cappella, R. Cerulli, C. J. Dai, F. A. Danevich, A. d'Angelo, S. d'Angelo, B. V. Crinyov, A. Incicchitti, V. V. Kobychev, B. N. Kropivyansky, M. Laubenstein, P. C. Nagornyi, S. S. Nagorny, S. Nisi, F. Nozzoli, D. V. Poda, D. Prosperi, A. V. Tolmachev, V. I. Tretyak, l. M. Vyshnevskyi, R. P. Yavetskiy, S. S. Yurchenko
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Anisotropy of Dark Matter Annihilation and Remnants of Dark Matter Clumps in the Galaxy V. Berezinsky, V. Dokuchaev, Yu. Eroshenko
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Current Observational Constraints on Inflationary Models E. Mikheeva
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Phase Transitions in Dense Quark Matter in a Constant Curvature Gravitational Field D. Ebert, V. Ch. Zhukovsky, A. V. Tyukov
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Construction of Exact Solutions in Two-Fields Models S. Yu. Vernov
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Quantum Systems Bound by Gravity M. L. Fil'chenkov, S. V. Kopylov, Y. P. Laptev
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CP Violation and Rare Decays Some Puzzles of Rare B-Decays A. B. Kaidalov
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Measurements of CP Violation in b Decays and CKM Parameters J. Chauveau
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Evidence for DO_Do Mixing at BaBar M. V. Purohit
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Search for Direct CP Violation in Charged Kaon Decays from NA48/2 Experiment S. Balev
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Scattering Lengths from Measurements of Ke4 and K± Decays at NA48/2 D. Madigozhin
7m
->
1T± 1T 01T O
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Rare Kaon and Hyperon Decays in NA48 Experiment N. M ala kana va
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THE K+ -> 1T+ vD Experiment at CERN Yu. Potrebenikov
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Recent KLOE Results B. Di Micco
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Decay Constants and Masses of Heavy-Light Mesons in Field Correlator Method A. M. Badalian
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Bilinear R-Parity Violation in Rare Meson Decays A. Ali, A. V. Borisov, M. V. Sidorova
303
Final State Interaction in K E. Shabalin
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->
21T Decay
Hadron Physics
Collective Effects in Central Heavy-Ion Collisions G. 1. Lykasov, A. N. Sissakian, A. S. Sarin, V. D. Toneev
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Stringy Phenomena in Yang-Mills Plasma V. 1. Zakharov
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Lattice Results on Gluon and Ghost Propagators in Landau Gauge I. L. Bogolubsky, V. G. Bornyakov, G. Burgio, E.-M. Ilgenfritz, M. Miiller-Preussker, V. K. Mitrjushkin
326
セ@
and 2: Excited States in Field Correlator Method I. Narodetskii, A. Veselov
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Theory of Quark-Gluon Plasma and Phase Transition E. V. Komarov, Yu. A. Simonov
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Chiral Symmetry Breaking and the Lorentz Nature of Confinement A. V. Nefediev
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Structure Function Moments of Proton and Neutron M. Osipenko
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Higgs Decay to bb: Different Approaches to Resummation of QCD Effects A. L. Kataev, V. T. Kim
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A Novel Integral Representation for the Adler Function and Its Behavior at Low Energies A. V. Nesterenko
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QCD Test of z-Scaling for nO-Meson Production in pp Collisions at High Energies M. Tokarev, T. Dedovich
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Quark Mixing in the Standard Model and the Space Rotations G. Dattoli, K. Zhukovsky
360
Analytic Approach to Constructing Effective Theory of Strong Interactions and Its Application to Pion-Nucleon Scattering A. N. Safronov
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New Developments in Quantum Field Theory On the Origin of Families and their Mass Matrices with the Approach Unifying Spin and Charges, Prediction for New Families N. S. Mankoc Borstnik
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Z2 Electric Strings and Center Vortices in SU(2) Lattice Gauge Theory M. 1. Polikarpov, P. V. Buividovich
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Upper Bound on the Lightest Neutralino Mass in the Minimal Non-Minimal Supersymmetric Standard Model S. Hesselbach, G. Moortgat-Pick, D. J. Miller, R. Nevzorov, M. Trusov
386
Application of Higher Derivative Regularization to Calculation of Quantum Corrections in N=l Supersymmetric Theories K. Stepanyantz
390
Nonperturbative Quantum Relativistic Effects in the Confinement Mechanism for Particles in a Deep Potential Well K. A. Sveshnikov, M. V. Ulybyshev
394
Khalfin's Theorem and Neutral Mesons Subsystem K. Urbanowski
398
Effective Lagrangians and Field Theory on a Lattice O. V. Pavlovsky
403
String-Like Electrostatic Interaction from QED with Infinite Magnetic Field A. E. Shabad, V. V. Usov
408
xix
QFT Systems with 2D Spatial Defects 1. V. Fialkovsky, V. N. Markov, Yu. M. Pismak
412
Bound State Problems and Radiative Effects in Extended Electrodynamics with Lorentz Violation 1. E. Prolov, O. G. Kharlanov, V. Ch. Zhukovsky
416
Particles with Low Binding Energy in a Strong Stationary Magnetic Field E. V. Arbuzova, G. A. Kravtsova, V. N. Rodionov
420
Triangle Anomaly and Radiatively Induced Lorentz and CPT Violation in Electrodynamics A. E. Lobanov, A. P. Venediktov
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The Comparative Analysis of the Angular Distribution of Synchrotron Radiation for a Spinless Particle in Classic and Quantum Theories V. G. Bagrov, A. N. Burimova, A. A. Gusev
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Problem of the Spin Light Identification V. A. Bordovitsyn, V. V. Telushkin
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Simulation the Nuclear Interaction T. F. K amalov
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Unstable Leptons and ({L- e - T}-Universality O. Kosmachev
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Generalized Dirac Equation Describing the Quark Structure of Nucleons A. Rabinowitch
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Unique Geometrization of Material and Electromagnetic Wave Fields O. Olkhov
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Problems of Intelligentsia
The Conscience of the Intelligentsia J. K. Bleimaier
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Conference Programme
463
List of Participants
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Fundamentals of Particle Physics
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THE QUANTUM NUMBER OF COLOR, COLORED QUARKS AND DYNAMIC MODELS OF HADRONS COMPOSED OF QUASIFREE QUARKS
v. Matveev a , A. Tavkhelidze b Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia Abstract. Are exposed the main stages of the early development of the hypothesis of the quantum number of color and of colored quarks
1
Introduction
At present, the dominant point of view is that all physical phenomena and processes, both terrestrial and cosmological, are governed by three fundamental forces: gravitational, electroweak and chromodynamic. The color charge serves as the source of chromo dynamic forces. In this talk we shall expose the main stages of the early development of the hypothesis of the quantum number of color and of colored quarks, put forward under the ideological influence of and in collaboration with N .Bogolubov at the JINR Laboratory of Theoretical Physics. In these works, the concept of color, colored quarks, was introduced for the first time, and a dynamical description of hadrons was given within the framework of the model of quasifree colored quarks. Introduction of the quantum number of color permitted to treat colored quarks as real physical objects, constituents of matter. Further, from the color 5U(3) symmetry, the Yang-Mills principle of local invariance and quantization of chromo dynamic fields gave rise to quantum chromo dynamics - the modern theory of strong interactions. 2
The quantum number of color and colored quarks
In 1964, when the hypothesis of quarks was put forward by Gell-Mann [lJ and Zweig [2], quarks were only considered to be mathematical objects, in terms of which it was possible, in a most simple and elegant way, to describe the properties, already revealed by that time, of the approximate unitary 5U(3) symmetry of strong interactions. At the beginning, these particles, exhibiting fractional charges and not observable in a free state, were not attributed the necessary physical interpretation. First of all, making up hadrons of quarks, possessing spin セL@ led to a contradiction with the Pauli principle and the Fermi-Dirac statistics for systems composed of particles of semiinteger spin. The problem of the quark statistics was not, however, the sole obstacle in the path of theory. No answer existed to the following question: why were ae-mail: [email protected] be-mail: [email protected]
3
4
only systems consisting of three quarks and quark-antiquark pairs realized in Nature, and why were there no indications of the existence of other multiquark states? Especially important was the issue of the possible existence of quarks in a free state (the problem of quark confinement). In 1965, analysis of these problems led N.Bogolubov, B.Struminsky and A.Tavkhelidze [3], as well as LNambu and M.Hana [4], and LMiyamoto [5] to the cardinal idea of quarks exhibiting a new, hitherto unknown, quantum number subsequently termed color. From the very beginning creation of the relativistically invariant dynamical quark model of hadrons was based, first of all, on the assumption of quarks representing real physical objects determining the structure of hadrons. To make it possible for quarks to be considered fundamental physical particles, the hypothesis was proposed by three authors (Bogolubov, Struminsky, Tavkhelidze - 1965, January) that the quarks, should possess an additional quantum number, and that quarks of each kind may exist in three (unitary) equivalent states q
==
(ql,q2,q3)
differing in values of the new quantum number, subsequently termed color. Since at the time, when the new quantum number was introduced, only three kinds of quarks were known - (u, d, s), the quark model with an additional quantum number was termed the three-triplet model. Since the new quantum number is termed color, colored quarks may be in three equivalent states, such as, for example, red, blue and green. With introduction of the new quantum number, color, the question naturally arised of the possible appearance of hadrons possessing color, which, however, have not been observed. From the assumption that colored quarks are physical objects, while the hadron world is degenerate in the new quantum number, or it is colorless, it followed that solutions of the dynamic equations for baryons and mesons in the s-state should be neutral in the color quantum numbers [4,6]. From the requirement that baryons be colorless, the wave function of the observed baryon family in the ground state, described by the totally symmetric 56-component tensor
114.4 GeV at 95% indirect from the precision data and the LEP working group 144 GeV if one includes the above direct limit but not including the new measurement in the conferences of last summer) and the latest Tevatron limits in [51. The theoretical upper limit for the is derived from unitarity arguments . vVF,VV. 2mz)
The best discovery channel is the "golden H -t -t 41 chanwhere the background is very small due to the constraint of the two reconstructed masses to be both compatible with the Z-mass. For the very masses (mH >700GeV) the decays H -t WW -t ZZ lllllJ, H -t ZZ -t lljj, due to their will enhance the discovery sensitivity and compensate for the lower T"','V11""''' cross-sections. 6 shows the overall sensitivity covering the full mass range. lnt',PU,."j,,,,rl luminosity corresponding to one year of low data takline) almost the full range is covered, provided that the detector
51
is optimal and well understood, Figure 6 summarizes the discovery potential for ATLAS as was calculated already in 2003 based on LO cross-sections. The update of this plot is expected soon.
Figure 6: The signal significance for a SM Higgs boson in ATLAS as a function of the Higgs mass for two different integrated luminosities.
4
SUPERSYMMETRIC HIGGS SEARCHES
In most common supersymmetric scenarios, the Minimal tiupel:Symrnet;nc bosons are tension of the SM (MSSM), five odd), . The discovery limits are commonly in terms of uc;"uuU5 a where contours in mA and tan/3 are drawn. The LEP2 results have excluded a of the plane (the low tan/3 region). In addition to the SM channels described above, the most DH)mlSlIlIl: rf'"'NY""""" V,uo,.,U",.", in the tan/3 region, are the J-LJ-L channels and the charged decays. The - t 'T'T a rate compared to the J-LJ-L one, but it is more reconstructed. On the other hand, the J-LJ-L one produces a very clean O'; Wb, Ht, Zt . As seen from Fig. 3, the Zt channel has small background but also a small event yield as opposed to the Wb channel which has an observability potential up to 2.5 TeV in 300 fb-1. The same integrated luminosity allows a 5 sigma discovery up to 1.4 Te V reach using the Z t channel. 4 ---
'" 0 0
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>
3.5-
'"
3
t1
2.5
t!l
ATLAS
0
セ@
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UJ
2" 1.5
0.5 2000 Invariant Mass (GeV)
2000 Invariant Mass (GeV)
Figure 3: Invariant mass reconstruction for an up type iso-singlet quark of mass 1 TeV using 300 fb- 1 integrated luminosity, Wb on the left and Zt on the right side.
New Leptons
New leptons, L, appear in various models [5,6,10]. The work in [11] concentrates on the lepton pairs produced from quark annihilation and from gluon fusion to a quark triangular loop. In both cases, the s channel contains the Z boson and a possible Z' as propagator. The first one can also propagate with a "y. The considered decay mode is L -> Zp, / Ze. The search was performed as a function of the new lepton and new heavy neutral gauge boson (Z') mass. The experimental reach is given in Fig. 4 for a Z' mass of 700 GeV. The lower (upper) curve is the reach for 10 (100) fb- 1 of integrated luminosity. A Z' of 2 Te V would increase the 5 cr reach from 800 Ge V to 1 Te V for 100 fb -1. Leptoquarks
Leptoquarks (LQ) are predicted by GUT and composite models. The study in [12] considered their pair production from gluon fusion and quark annihilation. The same work also covers the single production. The decay modes consist of electrons (type-I) or neutrinos (type-2) and a light jet. For both scalar and vector LQs, the mass scan was performed for different coupling coefficients.
59
'I8
7
200
eoo
6OC:
4(}O
lDC{1
1200
1400
M,
Figure 4: L reach as a function of its mass, low (high) luminosity corresponds to 10 (100) fb- 1 of integrated luminosity.
Fig. 5 summarizes the reach for 300 fb- 1 , showing that about 1.2 (1.5) TeV LQ can be discovered for scalar (vector) leptoquark models. til
_________ QPUGセ@
セ@
セ@
ATLAS
fLdt=3x10'W'
10 VlQType 1 _SLQTypel VLQ Type 2 SLQ Type 2
10
10
400
600
800
1000
1200
1400
1600
1800
Leptoquark mass, GeV
Figure 5: LQ reach as a function of its mass for 300 fb- 1 of integrated luminosity.
2.2
Searches for new gauge group structure
Embedding the 8M gauge group into a larger one brings additional gauge bosons, both neutral (Z/) and charged (WI). Additionally they appear in models with extra-dimensions (ED) as the Kaluza-Klein (KK) [13] excitations of their 8M counterparts.
60
Neutral gauge Hosons
A full GEANT MC simulation study was performed to investigate the Zl discovery potential of ATLAS using a generic parameterization called CDDT [14]. The CDDT parameterization classifies Zl searches into four distinct cases, depending on its coupling to the known fermions. In this study, a 1.5 and 4 TeV Zl produced by quark anti-quark annihilation was allowed to decay into e+epairs. The left side of Fig. 6 shows the ATLAS reach for 100 fb- 1 of integrated luminosity as a function of the ratio of the new gauge boson and its gauge coupling strength (Mz/g z ) and fermion coupling modification parameter (x) . A recent study investigated the discovery reach of the KK excitations of the Z boson, zn [15]. This model uses different parameterizations (A,B,C) to reproduce the known fermion masses and mixings. The right side of Fig. 6 shows the reconstruction of the zn invariant mass from e+e- pairs using a full GEANT based simulation together with the SM Drell-Yan background. The zn discovery reach for 100 fb- 1 integrated luminosity is up to 6 TeV, depending on the parameterization.
Figure 6: Left: generic Zl search with CDDT parameterization; Right: Zl invariant mass reconstruction for different fermion parameterizations. In both cases results with 100 fb- 1 are shown.
Charged gauge Hosons
Additional charged gauge bosons, W', appear in GUT, Little Higgs and ED models [6,8,18]. The quark anti-quark annihilation produces the W' that can be studied via its hadronic [16] or leptonic [17] decays. The important parameters are the W - W' mixing angle (cot B) and the mass of the W'. Fig. 7 shows the discovery reach for the WH search (Little Higgs model) , for 300 fb- 1 integrated luminosity in the cotB - mWH plane for the WH - t tb and W H - t ev modes.
Figure 7: WI discovery reach plane. The shaded area is from hadronic decay channel, dashed line is from electron decay.
Searches
new Electro-weak symmetry
mechanisms
variants of
Scalars
o
proposed for fermion and boson mass cヲBセtᄋゥGiyャ@ The studies in the context F."'Lv"", and scalars can predicted by both Little
,"U(U
additional vector bosons.
GセャBイ@ between the matter and force carrier solve the and fine tuning problems a candidate for the Dark Matter (DM) searches of
62
14()O
Figure 8: tl,±± search reach for single production on the left and for pair production on the right.
are expected to cascade decay down to the particle (LSP), the n jets + m leptons + channels are inv'es1;igl'1ted. The large number of free parameters can be reduced to 5 in case of [23] which proposes its LSP, the lightest neutralino, as the DM candidate. the reduced parameter set should also be consistent 9, left). A recent work has investigated the reach of with WMAP data pair production in the focus point scenario and ATLAS for and [24J. The result of the study is shown in background subtraction, for 10 fb- 1 of integrated significance.
""'''''T''.;"nrnn,,,t-,'l,,
Figure 9: Left: parameter space in mSUGRA. The medium gray region is consistent with WMAP data. Right: reconstructed 9 visible invariant mass for 1 fb- 1 of data.
63
2.4
Searches for new Dimensions
If the relative weakness of the gravitational force is attributed to the existence of extra dimensions (ED), the graviton becomes the object to search for. The graviton couples to all particles and can escape undetected. The most promising channels are gluon-gluon, quark-gluon fusion and quark anti-quark annihilation yielding one jet + missing E T . The experimental reach depends on the number of EDs and also the fundamental gravity scale. A study has shown that, for 100 fb- 1 of integrated luminosity, the reach would be about 9, 7 and 6 TeV, for 2, 3 and 4 additional dimensions [25]. Large (Te V- 1 ) EDs appearing in ADD models [26] predict KK excitations of gluons, g*, which would decay into heavy quark anti-quark pairs. A study evaluated the reach of ATLAS for the decay into bb and tf pairs [27]. Depending on the mass of the g*, it is possible to discover a g* with mass up to 3.3 TeV with an integrated luminosity of 300 fb- 1 • 3
Results and Conclusions
Although this note summarized only a selection of discovery possibilities, it has shown that ATLAS has a very rich discovery potential for physics beyond the SM. The differentiation between models and the possible boost to SM process cross sections from the particles proposed by the BSM physics were also not discussed. The preparation of the experimental apparatus for data taking is well underway, the new analyses with full simulation are also ongoing. These studies will immediately be applicable to first data from LHC. Acknowledgments
The author would like to thank A. Studenikin for his hospitality in Moscow and F. Ledroit and A. Parker for useful discussions. G.U.'s work is supported in part by U.S. Department of Energy Grant DE FG0291ER40679. References
[1] ATLAS Detector and Physics Performance Technical Design Report. CERN/LHCC/99-14/15. [2] LRiu, ATL-SLIDE-2007-05, proceedings of 15th IEEE Real Time Conference (2007). [3] E.J.Eichten, KD.Lane and M.E.Peskin Phys. Rev. Lett. 50, 811 (1983); L.Abbot, E.Farhi Phys.Lett., B 101,69 (1981). [4] A.Belyaev, C.Leroy, RMehdiyev, Eur.Phys.J. C 41, 1 (2005). [5] B.Holdom, JHEP 0608, 076 (2006); B.Holdom, JHEP 0703,063 (2007).
64
[6] F.Gursey, P.Ramond and P.Sikivie, Phys.Lett. B 60, 177 (1976); F.Gursey and M.Serdaroglu, Lett. Nuovo Cimento 21, 28 (1978). [7] RMehdiyev et al., Euro.Phys.J. C. 49, 613 (2007). [8] M.Schmaltz, Nucl.Phys. B 117, 40 (2003). [9] G.Azuelos et al., Euro.Phys.J. C. 39, Suppl.2, 13 (2005). [10] S.Dimopoulos Nucl.Phys. B 168, 69 (1981); E.Farhi, L.Susskind, Phys.Rev. D 20, 3404 (1979); J.Ellis et al., Nucl.Phys. B 182, 529 (1981). [11] C.Alexa, S.Dita, ATL-PHYS-2003-014 (2003). [12] A.Belyaevet al., J.H.E.P. 09, 005 (2005). [13] E.Witten, it Nucl.Phys. B186, 412 (1981). [14] F.Ledroit, B.'frocme, ATL-PHYS-PUB-2006-024, proceedings of TeV 4 LHC workshop, (2006). [15] F.Ledroit, G.Moreau, J.Morel, J.H.E.P. 09,071 (2007). [16] Gonzlez de la Hoz, S; March, L; Ros, E; ATL-PHYS-PUB-2006-003. [17] G.Azuelos et al., Eur.Phys.J. C 39,13 (2005). [18] L.Randall, RSundrum, Phys. Rev. Lett. 83, 3370 (1999). [19] LF.Ginzburg, M.Krawczyk, Phys.Rev. D72, 115013 (2005). [20] G.Azuelos, K.Benslama, J.Ferland, J.Phys. G 32, 73 (2006). [21] Y.Hosotani, Phys.Lett. B 126, 309 (1983) ; B.McInnes, J. Math. Phys. 31, 2094 (1990). [22] H.P.Nilles, Phys. Rev. 110, 1 (1984) and references therein. [23] A.H.Chamseddine, RArnowitt and P.Nath, Phys. Rev. Lett. 49 (1982) 970; H.P.Nilles, Phys.Rept. 110 (1984). [24] U.De Sanctis, T.Lari, S.Montesano, C.'froncon, arXiv:0704.2515, SNATLAS-2007-062, Eur.Phys.J. C52, 743 (2007). [25] L.Vacavant, LHinchliffe, J.Phys. G 27, 1839 (2001). [26] N.Arkani-Hamed, S.Dimopoulos, G.Dvali, it Phys.Lett. B 429, 96 (1998). [27] L.March, E.Ros, B.Salvachua, ATL-PHYS-PUB-2006-002 (2006).
THE STATUS OF THE INTERNATIONAL LINEAR COLLIDER B. Foster" Department of Physics, University of Oxford Denys Wilkinson Building, Keble Road, Oxford, OXl 3RH, UK Abstract. The status and prospects for the International Linear Collider are summarised.
The International Linear Collider (ILC) is accepted by the international community of particle physicists as the next major project in the field. The Global Design Effort (GDE), directed by Professor Barry Barish, has been charged by the International Committee for Future Accelerators with the task of preparing all necessary design and documentation to present a fully cos ted and robust design to the funding authorities by 2010, at which point the status of the Large Hadron Collider and other relevant information will be available to allow an informed decision on construction. The current status of the project is that the Baseline Design of January 2006 has been used as the basis for a greatly developed and refined reference design, summarised in the Reference Design Report [1], which in additional to descriptions of the major parts of the project, also gives a costing in ILC units ( = US$ 1 on Jan. 1st 2007) together with an estimate of the labour necessary to realised the project. The RDR estimates are 6.62 Billion ILCUs plus 14,100 person-years of effort. The Reference Design is based around a central campus containing a single interaction hall capable of hosting two detectors in a "push-pull" configuration, a damping ring complex for both electrons and positrons, the electron source and other central services. The damped electrons from the source are transported to the end of the superconducting modules and accelerated to an energy of 250 Ge V; part of the way along their path they are diverted through a wiggler which produces hard photons which are converted to electron-positron pairs. The positrons are selected and transported to the damping ring, damped and then transported to the other end of the machine to be accelerated in their turn and then collided with electrons at the interaction point. The RDR assumes that an accelerating gradient of 31.5 MV1m can be attained by each super conducting accelerating module. Many technical developments and specifications remain to be completed. The goal of 31.5 MV1m, although reached in some cavities, has not yet been achieved with the reproducibility and the yield necessary for the industrial production for the ILC. There are many remaining technical questions in areas such as the damping rings and a whole process of value engineering, optimisation and cost containment and reduction is required. This will be carried out ae-mail: [email protected]
65
66
in a third phase of the project, under the supervision of the GDE, known as the Engineering Design Report. This will be supervised by a Project management Team currently being set up and will begin in the autumn of 2007. At the same time as the technical and engineering developments for the ILC are progressing, it is important to develop political institutions and to explain the importance of the physics of the ILC both to politicians, other scientists and to the general public. The mechanism by which the site for the ILC will be bid for and chosen needs to be investigated and defined. The GDE welcomes the strong interest recently evinced by JINR Dubna in proposing Dubna as a possible site for the ILC and the interest expressed by the Russian Federation in exploring this possibility. It is also necessary to propose models and reach agreement on how a fully international project such as the ILC can be managed and governed to ensure accountability and transparency for stake-holders. The accomplishment of the technical aims of the EDR phase resulting in a proposal to construct the ILC in 2010 could lead, if prompt approval were granted, to ground breaking in 2012 and operation by 2019, allowing a substantial period of operation overlapping that of the LHC. The GDE is committed to maintaining such a timeline, defined as it is by the available effort and likely technical progress, while in parallel assisting the resolution of political questions and preparing an atmosphere conducive to approval of the ILC project. Reference
[1] G. Aarons et al., International Linear Collider Reference Design Report, available from http://www.linearcollider.org/cms/?pid=1000025, August, 2007.
REVIEW OF RESULTS OF THE ELECTRON-PROTON COLLIDER HERA
v. Chekelian (ShekeJyan) a Max Planck Institute for Physics, Foehringer Ring 6, 80805 Munich, Germany Abstract. A review of results of the electron-proton collider HERA is presented with emphasis on the structure of the proton and its interpretation in terms of
QeD.
1
Introduction
In summer 2007, after 15 years of successful operation, the first and only electron-proton collider HERA has finished data taking. The HERA collider project started in 1985 and produced the first ep collisions in 1992. It was designed to collide electrons with an energy of 27.5 GeV with protons with an energy of 920 GeV (820 GeV until 1997). This corresponds to a center of mass energy of 320 GeV. The maximum negative four-momentum-transfer squared from the lepton to the proton, Q2, accessible with this machine is as high as 100000 GeV2 . Two ep interaction regions were instrumented with the multi-purpose detectors of the HI and ZEUS collider experiments. In 2002, placing strong super-conducting focusing magnets close to the interaction points inside the HI and ZEUS detectors, the specific luminosity provided by the collider was significantly increased. At the same time spin rotators were installed in the HI and ZEUS detector areas, and since then a longitudinal polarisation of the lepton beams of 30-40% was routinely achieved. Over the 15 years of data taking, each collider experiment collected an integrated luminosity of :::::: 0.5jb- 1 , about equally shared between positively and negatively polarised electron and positron beams. The HERA physics program covers a broad spectrum of topics such as searches of new physics, hadron structure, diffractive processes, heavy flavour and jet production, vector meson production and many others. In this paper I will concentrate on results related to neutral current (NC) and charged current (CC) deep-inelastic scattering (DIS) and the QCD aspects of these measurements at HERA. 2
Deep-inelastic NC and CC ep scattering
The deep-inelastic NC scattering cross section can be written as (1) ae-mail: [email protected]
67
68 HERA II H1 Quark Radius Limit HERA 1+11 (417 pb")
"*
H1 e+pNC03..(l4(prel.)
t.
H1 e'p NC 2005 (pre •. )
g ...
o zeus e+p NC 2004 o
セ@
セ@
ZEUS e'p NC 04-05 (prel.
1.4 1.2
セ@ H1 e+p CC 03-04 (pre'.)
....
H1 e'p CC 2005 (prel.) ZEUS e+p CC 2004
•
ZEUS e'p CC O4-OS (pre •. )
セ@ セ@ セ@ セ@ セ[Zエッ。ョ」・イゥケ@
0.8 0_6
•
ヲMセ[i@
_
Rq =O.74'lO,'B m (95%CL)
1_4
1_' -I
.• _-- 8M e+p CC (CTEQ6M) -
NLセ⦅@
8M e-p NC (CTEC6M)
_
'*
. ___ Nセ@ ___• __ .. ___ .i
"0 -C
..... 8M e+p NC (CTEQ6M)
8M e'p CC (CTEQ6M)
L
0_'
y < 0.9 Pe=O
QPMW「NlセjゥSGャッ、@
Q'(GeV')
Q'(GeV')
Figure 1: The Q2 dependence of the NC and CC cross sections du/dQ2 for e±p scattering (left). The NC cross section normalised to the Standard Model expectation (right).
where a*,-c is the cross section in a reduced form, a is the fine structure constant, x is the Bjorken scaling variable, and y characterises the inelasticity of the interaction. The helicity dependence is contained in Y± = 1 ± (1 _ y2). The generalised proton structure functions, F2 ,3, occurring in eq.(l) may be written as linear combinations of the hadronic structure functions F 2 , Fi and fRセSG@ containing information on the QeD parton dynamics and the ・ャセ」ᆳ troweak couplings of the quarks to the neutral vector bosons. The function H is associated with pure photon exchange term, fセヲ@ correspond to photon-Z interference, and F.f,3 correspond to pure Z exchange terms. The longitudinal structure function FL may be decomposed in a similar way. The generalised proton structure functions depend on the charge of the lepton beam, on the lepton beam polarisation, defined as P = (NR - N L) / (NR + N L), where N R (Nd is the number ofright (left) handed leptons in the beam, and on the electroweak parameters Mz and sin 2 () (or Mw):
f,
+ k( -Ve =t= Pae)Fi z + k2(V; + a; ± 2Pvea e )Fl, k( -a e =t= Pve)xF;z + k2(2veae ± P(v; + a;»xFl.
F2± = F2
(2)
XF3± =
(3)
Here, k( Q2)
=
4 sin2
セ@
cos2
(1
qRセ@
z
determines the relative amount of Z to I
exchange, Ve = -1/2 + 2 sin () and ae = -1/2 are the vector and axial-vector couplings of the electron to the Z boson, and () is the electroweak mixing angle. At leading order in QeD the hadronic structure functions are related to linear combinations of sums and differences of the quark and anti-quark momentum 2
69 HERA Charged Current
*
* Hl e+p94-00
Hl e'p
a ZEUSe-p98-99
[J
ZEUSe+p99-00
-
SM e-p (CTE06D)
-
SM e+p (CTEQ6D)
Figure 2: The NC (left) and CC (right) double differential cross sections d 2uldxdQ2 in a reduced form for e+p and e-p DIS scattering.
distributions xq(x, Q2) and xij(x, Q2) of the proton: z (F2 , Fi , F2Z) = x セI・L@ (xF:;z,xF3Z)
2eqvq, v;
+ 。セIHア@
= 2x セI・ア。LカH@
+ ij),
(4)
- ij),
(5)
where Vq and a q are the vector and axial-vector couplings of the light quarks to the Z boson, and e q is the charge of the quark of flavour q. The deep-inelastic CC cross section can be expressed as d2a6c 27l'x dxdQ2 G}
(jac
[MrvMrv+Q2]2 =__acdx,Q ± 2 _ )-
1
2'
(±
±
Y+W2 =F LxW3 -
Y2W L±) ' (6)
is the cross section in a reduced form, G F is the Fermi constant, where and Mw is the mass of the W boson. W 2, XW3 and W L are the CC structure functions defined in a similar manner as for NC. In the quark parton model, where WL == 0, the structure functions W 2 and XW3 may be expressed as the sum and difference of the quark and anti-quark momentum distributions: + + W 2 = x(U + D), XW3 = x(D - U), W 2 = x(U + D), XW3 = x(U - D). The terms xU, xD, xU and xV are defined as the sums of up-type, of down-type and of their anti-quark-type distributions. The Standard Model (SM) predicts that in the absence of right-handed charged currents the e+p (e-p) CC cross section is directly proportional to the fraction of right-handed positrons (left-handed electrons) in the beam and can be expressed as (7)
70 1
N セm@
FL extraction from H1 data (for fixed W=276 GeV)
u.. X
2,
H1 +ZEUS Combined (pre)) 0.8
Q2=1500 GeV -
1.2
L.L'
1
NLOa,fit(Hl) NLO fit (ZEUS)
-
NLO (Alekhin)
:
j
......
NNLO (Alekhi") 1
I
Mi⦅B@
.""'"
Hl preliminary • Hl e·
0.8
0.6
-
•
H1 2000 PDF
[J
Hl e-
NlO MRST 2001
0.6
0.4 0.4 0.2
0.2
t'" 10
2
10
lセ@
1
x
...
セ
.. セ[G@ セエM[@
I
•
._
.,
...............................................................................• 10
i.
Q'/GeV'
Figure 3: The combined HI and ZEUS measurements of the structure function xF;;z (left). Summary of FL measurements by HI at a fixed photon-proton center of mass energy W = 276 GeV, W セ@ .;sy (right).
The HI and ZEUS measurements of the single differential NC and CC e±p cross sections dO' / dQ2 are summarised in Figure 1 (left). At low Q2 < 100 Ge V2 the cross section of the CC process mediated by the W boson, is smaller by 3 orders of magnitude compared to the NC process, due to the different propagator terms. At high Q2 セ@ the cross section measurements are approaching each other demonstrating the unification of the weak and electromagnetic forces. From a comparison of the NC measurements at highest Q2 with the SM expectation (see Figure 1, right), a limit on the quark radius of 0.74.10- 18 m is obtained [1], proving a point-like behaviour of the quarks down to about 1/1000 of the proton radius. The double differential NC and CC cross sections measurements [2] are shown in Figure 2. HERA allows to enlarge the coverage of the NC measurements by more than two orders of magnitude both in Q2 and x. The CC data provide information about individual quark flavours as can be seen in Figure 2 (right), especially at large Q2.
Mi, Mar
3
Structure functions F 2 , XF3 and FL
The NC cross section is dominated by the F2 contribution, and the reduced cross section, shown in Figure 2 (left), is essentially the proton structure function F 2 . In the figure one can see Bjorken scaling behaviour at x セ@ 0.13, positive scaling violation at higher x due to gluon radiation from the valence quarks and negative scaling violation for x < 0.13 due to sea quarks originated from gluons. At fixed Q2 one observes a steep rise of F2 towards low x. The region at low x is due to quarks which have undergone hard or multiple soft gluon radiation and which carry a low fraction of the proton momentum at the time of interaction. The rise of the proton structure function at low x is
71
セG[oゥS@ 10 • HI Data • ZEUS (pre!.) 39 pb- 1 .... MRST04 10
MRSTNNLO CTEQ6HQ HVQDIS + CTEQ5F4
Q2(GeV2)
Figure 4: The measured F!j" (left) and fセ「@
x=O.032
t
i=O
QoセPGRiB@
10'
10
セ@
Q2/Gey2
(right), shown as a function of Q2 for various x values.
one of the most surprising observations at HERA. It can be understood as an unexpected rapid increase of the gluon density towards low x. The structure function XF3 is obtained from the NC cross section difference between e-p and e+p data, i.e. XF3 = (y+/2Y_) [a-(x,Q2) -a+(x,Q2)]. The dominant contribution to XF3 arises from "(Z interference, which allows xF;z to be extracted according to xF;z ::= -xF3/kae neglecting the pure Z exchange contribution, which is suppressed by the small vector coupling Ve. This structure function is non-singlet and has little dependence on Q2. The measured xF;z at different Q2 values can thus be averaged taking into account the small Q2 dependence. The averaged xF;z determined for a Q2 value of 1500 Gey2 is shown in Figure 3 (left) [3]. In leading order QCD the interference structure function xF;z leads to the following sum rule:
r コセ@ 10 xF; 1
r -;- = 310 1
1
(2u v + dv)dx
5
= 3'
(8)
Higher order corrections to this are expected to be of order as /7r. In the range of acceptance, the integral of F;z is measured to be jッセVRU@ F;z dx = 1.21 ± 0.09(stat) ± 0.08(syst), which is consistent with the results of the HI and ZEUS QCD fits [4] of 1.12 ± 0.02 and 1.06 ± 0.02, respectively, for the same x interval at Q2 = 1500 Ge y2 . Non-zero values of the longitudinal structure function FL appear in perturbative QCD due to gluon radiation. According to eq. 1, the FL contribution to the inclusive cross section is significant only at high y. A direct way to measure
72 Charged Current ・セー@
Scattering e"p-JovX • H1 2005 (prel.) 0H198-99 '" ZEUS 04-05 (prel.) f:.ZEUS 98-99
e+p---JoVX • H199-04 ... ZEUS 06-07 (prel.) f:;ZEUS 99-00
60
..
r 0.8
f
0.6 0.4 0.2
CTEQ6D .... MRST2004
-0.2 -0.4
-0.6
-O.B
0'
DoCo',GM」セAッdPU@ P,
• A> • A
Hl 2000 PDF ZEUS-JETS PDF
10'
10
4
Figure 5: The dependence of the e+p and e-p CC cross-section on the lepton beam polarisation P (left). Measurements of the polarisation asymmetries A± in NC interactions (right).
FL is to explore the y dependence of the cross section at given x and Q2 by
changing the center of mass energy of the interaction. Such analysis at HERA is in progress now using dedicated data collected with lower proton beam energies of 460 and 575 GeV. Data at the nominal proton energy of 920 GeV have been used by the HI collaboration to determine FL which is responsible for the observed decrease of the Ne cross section at high y. A summary of these FL measurements by HI [5] is shown in Figure 3 (right). They are compared with QeD calculations and different phenomenological models, showing that already at the present level of precision the measurements can discriminate between different predictions.
4
Charm and bottom structure functions fセ」L@
F!/'
Heavy quark production is an important process contributing to DIS. It is expected to be well described by perturbative QeD at next-to-Ieading order (NLO), especially at values of Q2 greater than the square of the heavy quark masses. The charm and bottom contributions to the proton structure function Fie, fセ「@ are shown in Figure 4 [6]. They are measured using exclusive D or D* meson production and using a technique based on the lifetime of the heavy quark hadrons. In the latter case all events containing tracks with vertex detector information are used. The charm contribution on average amounts to 20 - 25% of F2 . The bottom structure function fセ「@ is measured at HERA for the first time. It is about 1/10 of the charm contribution and amounts to セ@ 2.5% of F2 at Q2 = 650 GeV 2 • The data are well described by QeD calculations. The accurate measurement of these structure functions is important to test the reliability of the theoretical framework used for the QeD analysis of
73
inclusive data and of predictions for the forthcoming LHC data, because their contribution is expected to be much increased at scales relevant for the LHC. 5
5.1
Polarisation effects in NC and CC
Polarisation dependence of the CC cross section
Measurements of CC deep-inelastic scattering with polarised leptons on protons allows the HERA experiments to extend tests of the V-A structure of charged current interactions from low-Q2, performed in the late seventies by the CHARM collaboration, into the high-Q 2 regime. ± The total CC cross sections 。セ、G@ as a function of the polarisation, measured in the range Q2 > 400 GeV 2 and y < 0.9, are shown in Figure 5 (left) [7]. The measurements agree with the SM predictions and exhibit the expected linear dependence as a function of the polarisation. Linear fits provide a good description of the data, and their extrapolation to the point P = 1 (P = -1) yields a fully right (left) handed CC cross section for e-p (e+p) interactions which is consistent with the vanishing SM prediction. The corresponding upper limits on the total CC cross sections exclude the existence of charged currents involving right handed fermions mediated by a boson of mass below 180 208 Ge V at 95% confidence level, assuming SM couplings and a massless right handed Ve.
5.2
Polarisation asymmetry in NC
The charge dependent longitudinal polarisation asymmetries of the neutral current cross sections, defined as (9)
measure to a very good approximation the structure function ratio, proportional to combinations aeVq, and thus provide a direct measure of parity violation. In the Standard Model A+ is expected to be positive and about equal to -A-. At large x the asymmetries measure the diu ratio of the valence quark distributions according to A± セ@ ±k(1 + dv /u v )/(4 + dv/u v ) . The combined HI and ZEUS data are shown in Figure 5 (right) [3]. The asymmetries are well described by the Standard Model predictions as obtained from the HI and ZEUS QCD fits [4]. The measured asymmetries A± are observed to be of opposite sign and the difference 6A = A+ - A- can be seen to be significantly larger than zero, thus demonstrating parity violation at very small distances, down to about 10- 18 m.
74
6: Parton distribution functions determined at HERA (left). Results on the weak neutral of the 'It quark to the Z boson as determined at HERA in comparison with similar results by the CDF experiment and the combined LEP experiments
Partonic structure of the
nJ'ntnn
The measurements of the full set of NC and CC douhle differential cross sections at HERA allow comprehensive QCD analyses to determine the and distributions inside the proton and the constant cross inclusive HERA measurements of the NC and CC HI and ZEUS performed NLO QCD fits [4), which lead to a decmnDositioln of the parton densities. In the fit their data are and gluon distributions obtained in the HI and fits are shown in 6 (left). The results agree within the error also agree with the parton densities from fits which bands. include not HERA but also fixed target DIS data as well as data from other processes sensitive to parton distributions, such as inclusive DI'()dllct:ion and the W-lepton asymmetry in collisions. The inclusive and CC cross sections are not distribution functions but also to the electroweak the NC cross section at depends on the weak vector (v q ) and axial-vector IlDI'HHno; of up- and down-type quarks to the Z boson via the structure functions. The longitudinal polarisation of the lepton beam additional to the couplings. This has been in a combined fit the PDFs and the electroweak parameters [8]. The fitted the u are shown in Figure 6 (right) in with similar suIts obtained the CDF experiment and the combined LEP The HERA determination has a better precision than that from the
75
tho UDeert.
HERA
セGL@
セLM
-'--, • ZEUS (inclusive-jet NC DIS) .,. ZEUS (inclusive-jet yp) ... ZEUS (norm. dijet NC DIS) III HI (norm. inclusive-jet NC DIS) . HI (event shapes NC DIS) Mセ@
- ,
Judu K-7r+. The analysis was done with 1 fb- 1 and was based on the SVT trigger [15] that allowed CDF to collect a large sample of Bf.) ---> h+h- decay modes (where h == K or 7r). A Maximum Likelihood fit which combines kinematic and particle identification information is performed to statistically determine the contribution of each mode and the relative contributions to the CP asymmetries. One of the new rare modes observed was bセ@ ---> K-7r+ with 8.2a. The direct CP assymmetry a」ーHbセ@ -> K-7r+) = 0.39 ± 0.15 ± 0.08. This value favors a large CP violation in bセ@ meson decays though it is also compatible with zero. A robust test of the SM or a probe of new physics suggested in ref. [21] is performed comparing the direct CP as-> K-7r+ and BO -> K+7r- decays. Using HFAG input [22] symmetries in bセ@ CDF measures r(BO -> K-7r+) - r(B O-> kKWイMIOHbセ@ -> K-7r+) - イHbセ@ -> K+7r-) = 0.84 ± 0.42 ± 0.15, in agreement with the 8M expectation of unity. CP violation in mixing in bセ@ -> J/iJI¢. An untagged sample of bセ@ -> J /iJI ¢ candidates represents a powerful tool to measure .6.r s, since a timedependent angular analysis of the decay products allows to disentangle the heavy (B.,H) and light (B.,L) Bs mass eigenstates. The decay bセ@ -> J/iJI¢
rise to both CP even and CP odd final states: since it is a lJ".'UUlU"'CctlitU vector-vector the final state can either have momentum = 0, or It is possible to separate the two CP components through the and measure the lifetime difference measure lifetimes in J jW¢i, CP states by basis the polar and azimuthal where the x-axis is defined by the the ¢i -+ and the 4) frame with respect to the np,,.,,,-,,"p simultaneous unbinned maximum-likelihood fit of the reconstructed mass, the lifetime and time distributions in order to extract CP even, CP odd DO is in two ways. First the ¢is has been fixed to zero, which assumes no New contribution in A non-zero width difference of .6.r s 0.12 ±0.08(stat.) ±0.03(syst.) has been obtained. both the width difference .6.r and a second fit to the DO = 0.17 ± AVAAVVViU.!".
where letter means that parameter is allowed to float in the fit). The obtained p - value is close to 0, 0.1): 22 %. shows the confidence and the confidence from this CDF mClepen1jerlt constraints on and ¢is [24J.
Figure 2: CDF (left) and DO (right) .6.r s, t/>s confidence region.
83
5
Results
To summarize, Both CDF and DO have performed a search for single top quark production using 1.5/0.9 fb- 1 of data collected at the Tevatron collider. Both find an excess of events over the background prediction in the high discriminant output region and interpret it as evidence for single top quark production. The excess has a significance of 3 standard deviations. The first measurement of the single top quark cross section yields: O'(pp --; tb+X, tqb+X) = 4.9±1.4 pb (DO), SNPセu@ pb (CDF). The cross section measurement is used to make the first direct measurement of the CKM matrix element Ivtbl without assuming CKM matrix unitarity, and find 0.68 < Ivtbl ::; 1 at 95% C.L for DO, Ivtbl > 0.55 at 95% C.L for CDF. We present CDF and DO results using 1.0/2.4 fb- 1 of data on the mixing system. CDF gets t:.ms = 17.77±0.10±0.07 frequency measurement in the bセ@ pS-l and DO gets t:.ms = 18.6 ± 0.8 pS-l. CDF uses its result to derive the ratio
Ivtd/vtsl
= セ@
セュ、@llms
mBg mBo
[25]. As inputs CDF uses mBo/mBos = 0.98390 [26]
with negligible uncertainty, t:.md = 0.507 ± 0.005 pS-l [25] and セ@ = 1.21 セァZェ@ [27]. CDF finds Ivtd/vtsl = 0.2060 ± 0.0007 (exp) セァZV@ (theor). Finnaly, a new series of measurements by the CD F and DO Collaborations has started to give unprecedented insights into the nature of CP violation nature in the bセM@ system. The CDF direct CP assymmetry a」ーHbセ@ --; K-7r+) = 0.39±0.15±0.08. With the HFAG input [22] CDF measures r(BD --; K-7r+)f(BD --; kKWイMIOヲHbセ@ --; K-7r+) - イHbセ@ --; K+7r-) = 0.84 ± 0.42 ± 0.15, in agreement with the SM expectation of unity. A non-zero decay width difference of t:.fs = 0.12 ± 0.08(stat.) ± 0.03(syst.) has been obtained by DO. In a second fit to the DO data, both the decay width difference t:.f and ¢. where floating parameters, which results in: t:.f s = 0.17 ± 0.09(stat.) ± 0.03(syst.), ¢. = -0.79 ± 0.56(stat.) ± O.Ol(syst.) CDF measures a t:.f. = PNWVセァZHウエ。Iᄆケ@ Regarding ¢., the obtained p - value is close to SM (t:.f. = 0, ¢. = 0.1): 22 %.
Acknowledgments I thank the organizers of the XIII Lomonosov Conference for a very enjoyable conference. I also thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundations, the European Community's Human Potential Programme and the Comision Interministerial de Ciencia y Tecnologia, Spain.
84
References [1] N. Cabibbo, Phys. Rev. Lett.l0, 531 (1963); M. Kobayashi and K. Maskawa, Prog. Theor. Phys. 49, 652 (1973). [2] D. Acosta et al. Phys. Rev. D, 71, 032001 (2005). [3] V.M. Abazov et al.,Nucl. Instrum. Methods A 565, 463 (2006). [4] A.P. Heinson, et al., Phys. Rev. D 56, 3114 (1997). [5] G.V. Jikia and S.R. Slabospitsky, Phys. Lett. B 295, 136 (1992). [6] W.-M. Yao et al., J. Phys. G: Nucl. Part. Phys. 33, 1 (2006), p. 142. [7] G.C. Blazey et al., in "Run II Jet Physics" (Proceedings ofthe Workshop on QCD and Weak Boson Physics in Run II) ed. by U. Baur, R.K. Ellis, and D. Zeppenfeld, Fermilab-Pub-00/297, 47, 1999. [8] L. Breiman et al., Classification and Regression Trees (Wadsworth, Stamford, 1984); D. Bowser-Chao et al., Phys. Rev. D 47, 1900 (1993). [9] V.M. Abazov et al., Nature 429,638 (2004); Phys. Lett. B 617,1 (2005). [10] R.M. Neal, Bayesian Learning of Neural Networks (Springer-Verlag, New York, 1996); P.C. Bhat and H.B. Prosper, "Statistical Problems in Particle Physics, Astrophysics and Cosmology", ed. by 1. Lyons and M.K. Unel (Imperial College press, London, 2006), p. 151. [11] 1. Bertram et al., Fermilab-TM-2104 (2000), and references therein; E.T. Jaynes and L. Bretthorst, Probability Theory: the Logic of Science (Cambridge University Press, Cambridge, 2003). [12] G.L. Kane, et al., Phys. Rev. D 45, 124 (1992). [13] V.M. Abazovet al., Phys. Rev. Lett. 98, 181802 (2007). [14] C. Grozis et al., Int. J. Mod. Phys. A 16S1C, 1119 (2001). S. Cabrera et al., Nucl. Instrum. Methods Phys. Res. A 494, 416 (2002). [15] W. Ashmanskas et al.,Nucl. Instrum. Methods Phys. Res. A 518 (2004). [16] A. Abulencia et al., Phys. Rev. Lett. 97, 062003 (2006). [17] A. Abulencia et al., Phys. Rev. Lett. 97, 242003 (2006). [18] V. M. Abazov et al., Phys. Rev. Lett. 97, 021802 (2006). [19] H. G. Moser and A. Roussarie, Nucl. Instrum. Methods Phys. Res., Sect. A 384, 491 (1997). [20] 1. Dunietz, R.Fleischer and U.Nierste, Preprint hep-ex/0012219. [21] H. J. Lipkin, Phys. Lett.B 621, 126 (2005). [22] E. Barberio et ai, Preprint hep-ex/0603003. [23] V.M.Abazovet al.,Phys.Rev.Lett. 95, 171801 (2005). [24] V.M.Abazovet al.,arXiv:hep-ex/0702030vl. [25] W.-M. Yao et al. J. Phys. G 33, 1 (2006). [26] D. Acosta et al., Phys. Rev. Lett. 96, 202001 (2006). [27] M. Okamoto, Proc. Sci. LAT2005 (2005) 013 [hep-lat/0510113j.
DIRECT OBSERVATION OF THE STRANGE b BARION 2t L. Vertogradov a
Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia Abstract. The first direct observation of the strange b baryon Bb (Bt) reconstructed from its decay mode Bb -t J/'!/JB-, with J/7/J -t J-t+J-t-, and B- -t A7r- -t (P7r-)7r- in pfi collisions at Vs = 1.96TeV is presented. Using 1.3jb- 1 of data collected by the DO detector 15.2 ± TNHウエ。IZAVセケ@ Bb candidates at a mass of 5.774 ± O.Ol1(stat.) ± O.015(syst.)GeV were observed. The significance of the signal is 5.5a.
The quark model of hadrons predicts the existence of a number of baryons containing b quarks. Despite significant progress in studying b hadrons over the last decade, only the Ab(udb) b baryon has been directly observed. The 2{; (dsb) (charge conjugate states are assumed throughout this report) is a strange b baryon made of valence quarks from all three known generations of fermions and is expected to decay through the weak interaction. Experiments at the CERN LEP e+e- collider have reported indirect evidence of the 2{; baryon based on an excess of same-sign 2-[- events in jets [2]. We observe the decay 2{; -+ JN2-, with IN -+ f,.L+f,.L-, 2- -+ A7r-, and A -+ P7r-. The analysis is based on a data sample of 1.3jb- 1 integrated luminosity collected in pp collisions at yfs=1.96 TeV with the DO detector at the Fermilab Tevatron collider during 2002 - 2006. The DO detector is described in detail elsewhere [3]. The components most relevant to this analysis are the central tracking system and the muon spectrometer. The central tracking system consists of a silicon microstrip tracker (SMT) and a central fiber tracker (CFT) that are surrounded by a 2 T superconducting solenoid. The SMT covers the pseudorapidity region 1771 < 3 (77 = -In [tan (8/2)] and 8 is the polar angle) while the CFT for 1771 < 2. The muon spectrometer is located outside the calorimeter and covers the pseudorapidity region 1771 < 2. It comprises a layer of drift tubes and scintillator trigger counters in front of 1.8 T iron toroids followed by two similar layers behind the toroids. The topology of 2{; -+ J N2- -+ J NA7r- decay is shown on Fig.1. The reconstruction of the J / 't/J and A and their selection are validated with simulated MonteCarlo(MC) 2{; events. The PYTHIA MC program [4] is used to generate 2{; signal events while the EvtGen program [5] is used to simulate 2{; decays. The 2{; mass and lifetime are set to be 5.840 GeV and 1.33 ps respectively, their default values in these programs. The generated events are subjected to the same reconstruction and selection programs as the data after passing through the DO detector simulation based on the GEANT package [6]. MC events are a e-mail:
[email protected]
85
86 reweighted to match the J 1'Ij; transverse momentum (PT) distribution observed in the data [7]. J 1'Ij; - t /-l+ /-l- decays are reconstructed from two oppositely charged muons that have a common vertex with X2 probability greater than 1%. Muons are identified by matching tracks reconstructed in the central tracking system with either track segments in the muon spectrometer or calorimeter energies consistent with the muon trajectory. They are required to have PT > 1.5 Ge V and at least one of them must be reconstructed in each of the three muon drift tube layers. Events containing a J 1'Ij; candidate are re-reconstructed with a version of the track reconstruction algorithm that increases the effciency for tracks with low PT and high impact parameters. For further analysis, J 1'Ij; - t /-l+ /-lcandidates are required to have mass 2.80 < MJjJj < 3.35 GeV and PT > 5 GeV. A - t pn- candidates are formed from two oppositely charged tracks that are consistent with originating from a common vertex with a X2 probability greater than 1% and that have a mass between 1.105 and 1.125 GeV. The two tracks are required to have a total of no more than two hits in the tracking detector before the reconstructed pn- vertex. Furthermore, the impact parameter significance (the impact parameter with respect to the event vertex divided by its uncertainty) must exceed three for both tracks and exceed four for at least one of them. The A candidates are then combined with negatively charged tracks (assumed to be pions) to form 3- - t An- decay candidates. The pion must have an impact parameter significance greater than three. The A and the pion are required to have a common vertex with a X2 probability of 1% or better. For both A and 3- candidates, the distance between the event vertex and its decay vertex is required to exceed four times its uncertainty. Moreover, the uncertainty of the distance between the production vertex and its decay vertex (decaylength) in the transverse plane (the plane perpendicular to the beam direction) must be less than 0.5 cm. The two pions from 3- - t An- - t (pn-)n- decays (right-sign) have the same charge. Consequently, the combination An+ (wrong-sign) events form an ideal control sample for background studies. Figure 2(a) compares mass distributions of the right-sign An- and the wrong-sign An+ combinations. The 3- mass peak is evident in the distribution of the right-sign events. A Anpair is considered to be a 3- candidate if its mass is within the range 1.305 < M A7T - < 1.340 GeV. 3b" - t J 1'lj;3- decay candidates are formed from J 1'Ij; and 3- pairs that are consistent with originating from a common vertex with a X2 probability greater than 8% or better and have an opening angle in the transverse plane less than n 12 rad. The uncertainty of the proper decay length of the J 1'lj;3vertex must be less than 0.05 cm in the transverse plane. A total of 2308
87
events remains after this preselection. The wrong-sign events are subjected to the same preselection as the right-sign events. A total of 1124 wrong-sign events is selected as the control sample. Several distinctive features of the 2/; ----tJ/1/J2- ----tJ/1/JA7r- ----t(p,+ p,-) (P7r- )7rdecay are utilized to further suppress backgrounds. The wrong-sign background events from the data and MC signal 2/; are used for studying additional event selection criteria. As shown in Fig. 2(b), the proton PT of background events peaks towards lower values. Therefore, protons are required to have transverse momenta greater than 0.7 GeV. Similarly, minimum PT requirements of 0.3 and 0.2 GeV are imposed on pions from A and 2- decays, respectively. These requirements remove 91.6% of the wrong-sign background events while keeping 60.3% of the MC 2/; signal events. Contamination from decays such as B- ----t Jj1jJK*- ----t J/1/JK°7r- and BO ----t J/1/JK*-7r+ ----t Jj1jJ(Kg7r-)7r+ are suppressed by requiring the 2- candidates to have decay lengths greater than 0.5 cm and cOS(Bcol) > 0.99, as 2- baryons are expected to have significant decay lengths. Here Bcol is the angle between the 2- direction and the direction from the 2- production vertex to its decay vertex in the transverse plane. These two requirements on the 2- reduce the background by an additional 56.4 %, while removing only 1.7% of the MC signal events. Finally, 2- baryons are expected to have a sizable lifetime. To reduce prompt backgrounds, the transverse proper decay, the transverse proper decay length significance of the 2/; candidates is required to be greater than two. This final criterium retains 82.0% of the MC signal events but only 43.9% of the remaining background events. In the data, 51 events with the 2/; candidate mass between 5.2 and 7.0 GeV pass all selection criteria. The mass range is chosen to be wide enough to encompass masses of all known b hadrons as well as the predicted mass of the 2/; baryon. The distribution of M(2/;) is shown in Fig.3(a). A mass peak near 5.8 GeV is apparent. A number of cross checks are performed to ensure the observed peak is not due to artifacts of the analysis: (1) Eighteen wrong-sign background events in the mass window 5.2 - 7.0 GeV survive the 2/; selection. The J/1/JA7r+ mass distribution, shown in Fig. 3(b), is consistent with a flat background. (2) The event selection is applied to the data events in the sidebands of the reconstructed 2- mass peak. The A7r- mass is required to be in the range 1.28 - 1.36 GeV excluding the 2- mass window 1.305 - 1.340 GeV while other criteria are kept the same. Similarly, the selection is applied to the J /1/J sideband events with 2.5 < MJ1,J1, < 2.7 GeV. The high-mass side band is not considered due to potential contamination from \[If events. The (p,+ p, -) (P7r- )7r- mass distributions of these sideband events are shown in Fig.3(c-d). No evidence of a mass peak is present for either distribution. (3) The possibility of a fake signal due to the residual b hadron background is investigated by applying the final 2/;
88 BO ----> jOGャェkセL@ and Ab ----> J/'ljJA selection to Me B- ----> J/'ljJK*- ----> jOGャェkセWイML@ samples with equivalent luminosities significantly greater than that of the data analyzed. No indication of a mass peak is observed in the reconstructed J /'ljJSmass distributions. (4) The mass distributions of J /'ljJ, S-, and A are investigated by relaxing the mass requirements on these particles one at a time for events both in the Sb signal region and the sidebands. The numbers of these particles determined by fitting their respective mass distribution are fully consistent with the quoted numbers of signal events plus background contributions. (5)The robustness of the observed mass peak is tested by varying selection criteria within reasonable ranges. All studies confirm the existence of the peak at the same mass.
Interpreting the peak as Sb production, candidate masses are fitted with the hypothesis of a signal plus background model using an unbinned likelihood method. The signal and background shapes are assumed to be Gaussian and flat, respectively. The fit results in a Sb mass of 5.774 ± 0.011 GeV with a width of 0.037 ± 0.008 GeV and a yield of 15.2 ± 4.4 events. Unless specified, all uncertainties are statistical. Following the same procedure, a fit to the Me Sb events yields a mass of 5.839 ± 0.003 GeV, in good agreement with the 5.840 GeV input mass. The fitted width of the Me mass distribution is 0.035±O.002 GeV, consistent with the 0.037 GeV obtained from the data. Since the intrinsic decay width of the Sb baryon in the Me is negligible, the width of the mass distribution is thus dominated by the detector resolution. To assess the significance of the signal, the likelihood, Ls+b, of the signal plus background fit above is first determined. The fit is then repeated using only the background contribution, and a new likelihood Lb is found. The logarithmic likelhood ratio J2ln(L s+b/ Lb) indicates a statistical significance of 5.5u, corresponding to a probability of 3.3 x 10- 8 from background fluctuation for observing a signal that is equal to or more significant than what is seen in the data. Including systematic effects from the mass range, signal and background models, and the track momentum scale results in a minimum signicance of 5.3u and a Sb yield of 15.2 ± TNHウエ。IAVZセケ@
Potential systematic biases on the measured Sb mass are studied for the event selection, signal and background models, and the track momentum scale (see more at [1]). So, the resulting measured Sb mass is: 5.774 ± O.Ol1(stat.) ± O.015(syst.) GeV.
A lot of thanks to my DO b-Physics group colleagues, the staffs at Fermilab and collaborating institutions.
89
Figure 1: Decay topology of the :=:;; --> J /1/1:=:- where J /1/1 -> J.t+ J.t- and :=:- --> A7r- --> HpWイMIセN@ The:=:- and A baryons have decay lengths of the order of cm; the :=:;; has an estImated decay length of the order of mm (IP is the primary Interaction Point).
セ@
(a)
セ@
lD13,1.310'
2!
400t
t
;-
o'
セSP{@
right-sign wrong-sign ,
:> セ@
D13, 1.310'
(b)
350 - Me: ウセ@ signal ........ Data: wrong-sign
'H
I:
セ@
200
W
1.28
1.3
1.32 1.34 1.36 M(An) [GeV)
Figure 2: (a) The effective mass distribution of the A7r pair before the :=:;; reconstruction. Filled circles are from the right-sign A7r- combinations showing a :=:- mass peak while the histogram is from the wrong-sign A7r+ combinations. (b) Distributions of the proton transverse momentum of the wrong-sign background events (dotted histogram) and Monte Carlo signal :=:;; events (solid histogram) after preselection. The signal distribution is scaled to the same number of background events.
90
-
(a)
>Q)
G It)
0121,1.3 fb· 1
4 3
wrong-sign DI2I, 1.3 fb· 1
S
0
...J Data ..... Fit
c:i
セ@ _6
J94 3
s:: Q) >
UJ
(b)
5i
Jj2
4
1
(d) 2
0
5.5
6 mHsセI@
6.5
7
(GeV]
Figure 3: (a) The invariant mass distribution of the :=:;; candidates after all selections. The dotted curve is an unbinned likelihood fit to the model of a constant background plus a Gaussian signal. (b - d) The (f.1,+ f.1,- ) (p-rr- )-rr- invariant mass distributions of the wrong-sign background, J/'I/J sideband, and:=:- sideband events.
References
[1] V.M. Abazov et ai. (DO Collaboration), Phys.Rev.Lett. 99, 1052001(2007). [2] J. Abdallah et al. (DELPHI Collaboration), Eur. Phys.J. C44, 299(2005); D.Buskulic et al. (ALEPH Collaboration), Phys.Lett.B 384, 449(1996). [3] V.M. Abazov et al. (DO Collaboration), Nucl. lnstrum. Methods A565, 463(2006). [4] T. Sjostrand et al., Comput. Phys. Commun. 135, 238 (2001). [5] D.J. Lange, Nucl. lnstrum. Methods A462, 152(2001). [6] R. Brun and F. Carminati, CERN Program Library Writeup W5013, 1993 (unpublished). [7] V.M. Abazov et al.(DO Collaboration), Phys.Rev.Lett. 98, 121801(2007). [8] W.-M. Yao et al., Journal of Physics G33, 1(2006).
SEARCH FOR NEW PHYSICS IN RARE B DECAYS AT LHCb V. Egorychev a on behalf of the LHCb collaboration Institute for Theoretical and Experimental Physics, 117218 Moscow, Russia Abstract.We discuss the potential of the LHCb experiment to study rare B decays and their impact on various scenarios for New Physics. Some possible experimental strategies are presented.
1
Introduction
Rare decays in the beauty sector encompass a wide range of processes offering exceedingly valuable tool in the search for New Physics (NP) as well as in precision measurements of the Standard Model (SM) parameters, e.g. the Cabbibo-Kobayashi-Maskawa (CKM) matrix elements. The focus of this paper is made on the processes with the final states containing photons or leptons in addition to daughter hadron(s). The examples considered include the electromagnetic or electroweak penguin decays B --+ K*" Bs --+ ¢,' B --+ K*f+Cand the dilepton decay Bs --+ p,+ p,-. Most of these rare decays correspond to diagrams with internal loops or boxes leading to effective flavor-changing neutral current (FCNC) transitions. Presence of new virtual particles (e.g. the supersymmetric ones) with masses of the order of 100 GeVjc 2 may manifest itself in altering the decay rate, C P asymmetry and other observable quantities. Exciting new perspectives for the B physics emerge owing to the large statistics to be collected by the LHCb experiment, which will enable to enter a new realm of high precision studies of rare B decays.
2
LHCb experiment
The LHCb experiment features a forward magnetic spectrometer with a polar angle coverage of 15-300 mrad and a pseudo-rapidity range of 1.8 < 'f} < 4.9 [1). In order to maximize the probability of a single interaction per bunch crossing, it was decided to limit the luminosity in the LHCb interaction region to '" 2 X 1032 cm- 2 8- 1 . This has the additional advantage of limiting the radiation damage due to the high particle flux at small angles. The bb cross-section at the nominal LHCb luminosity is large enough to produce'" 10 12 bb pairs per year (10 7 s). The detector consists of a silicon vertex locator, followed by a first Ring Imaging Cherenkov Counter (RICH), a silicon trigger tracker, a 4 Tm spectrometer dipole magnet, tracking chambers, a second RICH detector, a calorimeter system and a muon identifier. One of the main features is a versatile trigger with a 2 kHz output rate dominated by pp --+ bbX events. The reconstruction of rare a e-mail:
[email protected]
91
Figure 1: The integrated luminosity required to achieve a 3 K*y candidates (the blue filled histogram represents combinatorial background).
B decays at LHCb is a challenge due to their small rates and large backgrounds from various sources. The .B-mesons are separated from .the large background produced directly at the interaction point in a detached vertex analysis by exploiting the relatively long lifetime of B-meson and a large average transverse momentum (pr) of the B-meson decay products. Therefore, the signature for a B event is based upon selection of particles with high px coming from a displaced vertex. The most critical backgornnd is the combinatorial background from pp -> bbX events, containing secondary verteces and characterized by high charged and neutral multiplicities. 3 The search for Bs —> fi+fj,^ The decay Ba —> /A+ fi~ is highly suppressed in the SM, since it can only be produced through a box diagram or a Z penguin. The current SM prediction is Br{Ba —> (J,+IJ,~~) = (3.4±0.5) x 10^9 [2]. In some new physics scenarios, the branching fraction can be enhanced by a high power of tan/? (e.g. Br oc tan6 /?), where tan/? is the ratio of the Higgs vacuum expectation values. For large values of tan/?, the branching fraction could be enhanced by two orders of magnitude, which is currently within the reach of the CDF and DO experiments. The large background (unlike sign muons originating from B decays or B decays into hadrons which are misidentified as muons) expected in the search for this decay is kept under control thanks to an excellent tracking performance of LHCb (namely the invariant mass resolution for dimuons ~ 18 MeV/e2), a good particle identification and good vertex resolution. The LHCb sensitivity
93
as a function of integrated luminosity is shown in Fig 1. LHCb has the potential to claim a three standard deviation observation at the level of the 8M prediction with", 2jb- 1 whereas a five standard deviation observation would require about 10 jb- 1 [3]. 4
The search for NP in b ---; sry and b ---; s£+ £-
Phenomenologically the b ---; sry and b ---; s£+ £- decays are closely linked. 8M calculations for these rare decays are performed using an effective Hamiltonian that is written in terms of several short-distance operators [4]. The process b ---; sry is dominated by the photon penguin operator, with Wilson coefficient C7 , while b ---; s£+£- has contributions also from semileptonic vector and axialvector operators with Wilson coefficients C9 and C lO respectively. To further pin down the values of these coefficients, it is necessary to exploit interference effects between the contributions from different operators. This is possible in the exclusive decay B --7 K*£+£- decays by measuring the forward-backward asymmetry AFB(q2), the longitudinal polarisation fraction of the K*o FL and the second of the two polarisation amplitude asymmetries aセIN@ 4·1
Electroweak penguin decay bセ@
--7
K* fJ.,+ fJ.,-
The decay bセ@ --7 K* fJ.,+ fJ.,- is loop-suppressed in the 8M, bイHセ@ ---; K* fJ.,+ fJ.,-) = HQNRセァZ@ x 10- 6 ) [5]. NP contributions could drastically change the shape of the AFB(q2) curve. For example, the sign of AFB(q2) can be flipped, the zero-crossing point may be shifted, or AFB(q2) may not even cross zero [6J. The procedure is to measure the AF B asymmetry of the angular distribution of daughter fJ.,+ relative to the B direction in the fJ.,+ fJ.,- rest frame as a function of the fJ.,+ fJ.,- invariant mass. The expected number of events in one year of data taking (2 jb- 1 ) by LHCb is 7200 ± 2100 (the error is due to the branching ratio), with a background-to-signal ratio B / S < 0.5 [7]. LHCb expects to extract the C9 /C7 Wilson coefficients ratio from the value of the fJ.,+ fJ.,- invariant mass for which the AFB is equal to zero to a precision of 13% after 5 years of running (10 jb- 1 ). Taking into accout the expected background level, the resolution with 2jb- 1 of integrated luminosity is 0.016 in FL and 0.42 in aセI@ [8].
4.2
Radiative decays b --7 sry
The polarization of the photons emitted in the b --7 sry transition provides an important test of the 8M, which predicts most left-handed photons. In the LHCb experiment these radiative decays can be reconstructed in the modes Bd --7 K*ry, Bs --7 ¢ry or Ab --7 Ary. The reconstruction procedures for Bd,s --7 K*(¢h decays are similar. To suppress the background from Bd,s --7 K*(¢)7r° in which the 7r 0 is misidentified as a single photon, a cut on the angle between
94 Table 1: Annual yields and background-to-signal ratios for radiative Ab decays (upper limits calculated at 90 % C ... L)
channel Ab -; ky Ab -; A(1520)-"y Ab -; A(1670)-"y Ab -; A(1690)-"y
yield/2 jb- 1 750 4.2 x 10 3 2.5 x 103 4.2 x 103
B/S 42 10 18 18
< < <
7 respectively, leading to 0'(')') rv 4° under the assumption of perfect U-spin symmetrye. 4
Outlook
With an accumulated luminosity of 10 fb- 1 LHCb will be able to measure the angle 'Y to a precision 0' stat rv 5° from tree-mediated processes, 0' stat rv 2° from processes where NP could enter DO mixing, and O'stat rv 2° (under U-spin symmetry assumption) from processes involving penguin loops, thus providing a powerful probe for NP. The Bs mixing phase 1>s will be measured to a precision O'stat rv 0.01 providing a constraint on NP by comparing tree-mediated with pure penguin processes. References [1] LHCb Collaboration, LHCb Reoptimized Detector Design and Performance TDR, CERN LHCC 2003-30. [2] B. Spaan, talk at this conference. [3) V. Egorychev, talk at this conference. [4] G.F. Tartarelli, Eur.Phys.J.direct C4S1 (2002) 35. [5] Z. Ligeti et al., hep-ph/0604112. [6] S. Cohen, M. Merk, E. Rodrigues, CERN-LHCb-2007-041. [7] M. Gronau, D. London, Phys.Lett. B253 (1991) 483; M. Gronau, D. Wyler, Phys.Lett. B265 (1991) 172. [8] D. Atwood, I. Dunietz, A. Soni, Phys.Rev.Lett. 78 (1997) 3257. [9] A. Giri, Yu. Grossman, A. Soffer, J. Zupan, Phys.Rev. D78 054018 (2003). [10] M. Patel, CERN-LHCb-2007-043; V. Gibson, C. Lazzeroni, J. Libby, CERN-LHCb-2007-048; K. Akiba, M. Gandelman, CERN-LHCb-2007050; J. Libby, A. Powell, J. Rademacker, G. Wilkinson, CERN-LHCb2007-098. [11] R. Fleischer, Phys.Lett. B459 (1999) 306. [12] J. Nardulli, talk at the 4th Workshop on the CKM Unitarity Triangle, December 2006.
eSensitivity of the method degrades with the U-spin symmetry breaking [12]. With no constraints on OTrTr,K K and 20% breaking of d TrTr = dK K, O'(-y) "" 10°. The method is believed to fail for larger U -spin symmetry breaking.
COLLIDER SEARCHES FOR EXTRA SPATIAL DIMENSIONS AND BLACK HOLES Greg Landsberg a Brown University, Department of Physics, 182 Hope St., Providence, RI02912, USA Abstract. Searches for extra spatial dimensions remain among the most popular new directions in our quest for physics beyond the Standard Model. High-energy collider experiments of the current decade should be able to find an ultimate answer to the question of their existence in a variety of models. We review these models and recent results from the Tevatron on searches for large, TeV-1-size, and Randall-Sundrum extra spatial dimensions. The most dramatic consequence of low-scale Hセ@ 1 TeV) quantum gravity is copious production of mini-black holes at the LHC. We discuss selected topics in the mini-black-hole phenomenology.
1
Models with Extra Spatial Dimensions
A new, string theory inspired paradigm [1] proposed by Arkani-Hamed, Dimopoulos, and Dvali (ADD) in 1998 suggested the solution to the hierarchy problem of the standard model (SM) by introducing several (n) spatial extra dimensions (ED) with the compactification radii as large as セ@ 1 mm. These large extra dimensions are introduced to solve the hierarchy problem of the SM by lowering the Planck scale to a TeV energy range. (We further refer to this fundamental Planck scale in the (4+n)-dimensional space-time as MD') In this picture, gravity permeates the entire multidimensional space, while all the other fields are constrained to the 3D-space. Consequently, the apparent Planck scale M p1 = l/JGN only reflects the strength of gravity from the point of view of a 3D-observer and therefore can be much higher than the fundamental (4+n)-dimensional Planck Scale. The size of large extra dimensions (R) is fixed by their number, n, and the fundamental Planck scale MD. By applying Gauss's law, one finds [1,2]: mセャ@ = 87rM£;+2 Rn. If one requires MD セ@ 1 TeV and a single extra dimension, its size has to be of the order of the radius of the solar system; however, already for two ED their size is only セ@ 1 mm; for three ED it is セ@ 1 nm, i.e., similar to the size of an atom; for larger number of ED it further decreases to subatomic sizes and reaches セ@ 1 fm for seven ED. Almost simultaneously with the ADD paradigm a very different low-energy utilization of the idea of compact extra dimensions has been introduced by Dienes, Dudas, and Gherghetta [3]. In their model, additional dimension(s) of the "natural" EWSB size of R セ@ 1 TeV- 1 [4] are added to the SM to allow for low-energy unification of gauge forces. In conventional SM and its popular extensions, such as super symmetry, gauge couplings run logarithmically with energy, which is a direct consequence of the renormalization group evolution (RGE) equations. Given the values of the strong, EM, and weak couplings at low energies, all three couplings are expected to "unify" (i.e., reach the same ae-mail: [email protected]
99
100
strength) at the energy'" 10 13 TeV, know as the Grand Unification Theory (GUT) scale. However, if one allows gauge bosons responsible for strong, EM, and weak interactions to propagate in extra dimension(s), the RGE equations would change. Namely, once the energy is sufficient to excite Kaluza-Klein (KK) modes of gauge bosons (i.e., '" 1I R '" 1 Te V), running of the couplings is proportional to a certain power of energy, rather than its logarithm. Thus, the unification of all three couplings can be achieved at much lower energies than the GUT scale, possibly as low as 10-100 TeV [3]. While this model does not incorporate gravity and thus does not explain its weakness relative to other forces, it nevertheless removes another hierarchy of a comparable size - the hierarchy between the EWSB and GUT scales. In 1999, Randall and Sundrum offered a rigorous solution [5] to the hierarchy problem by adding a single extra dimension (with the size that can range anywhere from", 1/MpI virtually to infinity) with a non-Euclidean, warped metric. They used the Anti-deSitter (AdS) metric (i.e. that of a space with a constant negative curvature) ds 2 = exp( -2kRI Vr oscillations and the unphysical region of sin 2(2B 23 ) > 1 is excluded. The impact of the systematic effects on the measurement is assessed by performing oscillation fits to simulated data sets with the corresponding systematics applied. The most significant sources of systematic error are found to be the uncertainty in the near to far normalization (4%), the absolute hadronic shower energy scale (10%) and the neutral current normalization (50%). These systematic uncertainties are incorporated in the oscillation fit as nuisance parameters. From the best fit values of the oscillation fit we obtain the neutrino squared-mass difference ャセュRQ@ = (2.38:t.:g:ig) x QoセS・vR@ and mixing angle with errors quoted at the 68% confidence level. The sin 2(2B 23 ) = QNPセoX@ best oscillation fit corresponds to X 2 = 41.2 for 34 degrees of freedom and is shown alongside the data in the left plot of Figure 1. The best fit point and the 68% and 90% confidence intervals in oscillation parameter space can be seen on the right plot of Figure 1. 3
Prospects
As the beam data continues to be collected we anticipate a significant increase to our vI" disappearance sensitivity, as shown on the left plot of Figure 2. Beyond these results, there is the possibility that MINOS could make the first measurement of a non-zero B13 if this mixing angle lies in the vicinity of the current experimental limit set by CHOOZ [8]. Even though MINOS does
116 Oscillation Results lor 2.50E20 POTs
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MINOS PrBlimlflary
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100
80 60 40 20 10
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Figure 1: (left) Reconstructed CC vJ.L energy spectrum in the FD for the null prediction (black), the best fit (red) and the data (points). (right) The new MINOS best fit point (star) along with the 68% and 90% contours. Overlaid are the 90% contours from the Super-Kamiokande zenith angle [5] and LIE analyses [6], as well as that from the K2K experiment [7].
not have the optimal granularity for separating between electromagnetic and hadronic showers several techniques have been devised that successfully select CC Ve events. The background consists primarily of NC and CC vI" events and is predicted using the ND data. With the existing data set our sensitivity to 813 is comparable or better to the current best limit as obtained by CHOOZ, and a first result is expected in 2008. With the full data set a discovery will be made or the current best limit reduced by about a factor of 2. By selecting for short and diffuse showers MINOS has the capability of identifying NC events with high efficiency (rv 90%) and purity (rv 60%). Given that NC events are unaffected by standard three-flavor neutrino oscillations any depletion of NC events at the FD detector would be an indication of oscillations to sterile neutrinos. The left plot of Figure 2 shows the MINOS sensitivity to the fraction of sterile mixing is defined as the fraction of disappearing vI-' 's that oscillate to sterile neutrinos. A result for this analysis is expected very soon. Its almost unprecedented ability for distinguishing between positive and negative neutrino induced muons makes MINOS an ideal ground for studying the physics of muon anti-neutrinos. For instance the FD data will be searched for exotic vI" ---+ TJI" transitions. Such transitions are predicted by some models beyond the Standard Model [9] and, it has been speculated, could explain the muon neutrino deficit observed in atmospheric neutrino experiments [10]. An anti-neutrino oscillation analysis is also in the works. Such a measurement would constitute a direct test of CPT conservation in the neutrino sector and could have a strong impact on CPT violating models introduced to, for example, expain the LSND signal [11]. In order to maximize the sensitivity to CC TJ I" disappearance we are currently studying the possibility of running with the horn current reversed for a small period of time. In such a configuration
117 MINOS Sensitivity as a function of Integrated POT
r
0.004
'.1o:1l10 GeV) in 1998-2002 are shown in Fig. 3. It was shown [12-14] that the size of a cone which contains 90% of signal strongly depends on neutralino mass. 90% C.L. flux limits are calculated as a function of neutralino mass using cones which collect 90% of the expected signal and are corrected for the 90% collection efficiency due to cone size. Also a correction is applied for each neutralino mass to translate from 10 GeV to 1 GeV threshold (thus modifying the results as presented earlier for 10 GeV threshold [15]). These limits are shown in Fig. 4. Also shown in Fig. 3, and Fig. 4 are limits obtained by Baksan [12], MACRO [13], Super-Kamiokande [14] and AMANDA (from the hard neutralino annihilation channels) [16]. 2.3
A search for fast magnetic monopoles
Fast magnetic monopoles with Dirac charge g = 68.5e are interesting objects to search for with deep underwater neutrino telescopes. The intensity of monopole Cherenkov radiation is セ@ 8300 times higher than that of muons. Optical modules of the Baikal experiment can detect such an object from a distance up to hundred meters. The processing chain for fast monopoles starts with the selec-
124
tion of events with a high multiplicity of hit channels: Nhit > 30. In order to reduce the background from downward atmospheric muons we restrict ourself to monopoles coming from the lower hemisphere. For an upward going particle the times of hit channels increase with rising z-coordinates from bottom to top of the detector. To suppress downward moving particles, a cut on the value of the time-z-correlation, Ctz , is applied: "Nhit(t· - l)(z· - z)
Ctz =
L..,,-l' , Nhit(jt(jz
>0
(1)
where ti and Zi are time and z-coordinate of a fired channel, I and z are mean values for times and z-coordinates of the event and (jt and (jz the rms-errors for time and z-coordinates. 10',-----------------------,
MACRO
10. 10 -"'1セMGAPNB]X」VL@
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Time-coordinate correlation
Figure 5: C tz distributions for experimental events (triangles), simulated atmospheric muon events (solid), and simulated upward moving relativistic magnetic monopoles (dotted); mUltiplicity cut Nhit > 30.
17
L.._ _---'-_ _---'-_ _-'--_-'--_....l
0.5
0.6
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B = vIc Figure 6: Upper limits on the flux of fast monopoles obtained in this analysis (Baikal) and in other experiments.
In Fig. 5 we compare the Ctz-distribution for experimental data (triangles) and simulated atmospheric muon events (solid curve) with simulated upward moving monopole events (dotted curve). Within 1038 days of live time using in this analysis, we have selected 20943 events satisfying cut 0 (Nhit > 30 and C tz > 0). For further background suppression (see [17] for details of the analysis) we use additional cuts, which essentially reject muon events and at the same time only slightly reduce the effective area for relativistic monopoles* : (1) Nhit > 35 and Ctz > 0.4 -;- 0.6 (2) X2 determined from reconstruction has to be smaller than 3 (3) Reconstructed zenith angle () > 100° (4) Reconstructed track distance from NT200 center R rec > 10 -;- 25 m . • Different values of cuts correspond to different NT200 operation configurations.
125
No events from the experimental sample pass cuts (1)-(4). The acceptances f3 =1, 0.9 and 0.8 have been calculated for all NT200 operation configurations (various sets of operating channels). For the time periods included, AefJ varies between 3· lOB and 6· lO Bcm 2sr (for f3 = 1). From the non-observation of candidate events in NT200 and the earlier stage telescopes NT36 and NT96 [18], a combined upper limit on the flux of fast monopoles with 90% C.L. is obtained. Upper limit on a flux of magnetic monopoles with f3 1 is 4.6· 1O-17cm-2s-1scl. In Fig. 6 we compare our upper limit for an isotropic flux of fast monopoles obtained with the Baikal neutrino telescope to the limits from the underground experiments Ohya [19] and MACRO [20] and to the limit reported for the underice detector AMANDA B10 [21] and preliminary limit for AMANDA II [22]. AeJJ for monopoles with
2.4
A search for extraterrestrial high-energy neutrinos
The BAIKAL survey for high energy neutrinos searches for bright cascades produced at the neutrino interaction vertex in a large volume around the neutrino telescope [3]. We select events with high multiplicity of hit channels Nhib corresponding to bright cascades. To separate high-energy neutrino events from background events a cut to select events with upward moving light signals has been developed. We define for each event tmin = min(ti - tj), where ti, tj are the arrival times at channels i, j on each string, and the minimum over all strings is calculated. Positive and negative values of tmin correspond to upward and downward propagation of light, respectively. Within the 1038 days of the detector live time between April 1998 and February 2003, 3.45 x lOB events with Nhit セ@ 4 have been recorded. For this analysis we used 22597 events with hit channel multiplicity Nhit >15 and tmin >-10 ns. We conclude that data are consistent with simulated background for both tmin and Nhit distributions. No statistically significant excess above the background from atmospheric muons has been observed. To maximize the sensitivity to a neutrino signal we introduce a cut in the (tmin, Nhit) phase space. Since no events have been observed which pass the final cuts upper limits on the diffuse flux of extraterrestrial neutrinos are calculated. For a 90% confidence level an upper limit on the number of signal events of n90% =2.5 is obtained assuming an uncertainty in signal detection of 24% and a background of zero events. A model of astrophysical neutrino sources, for which the total number of expected events, N m , is large than ngO%, is ruled out at 90% CL. Table 1 represents event rates and model rejection factors (MRF) ngo%/Nm for models of astrophysical neutrino sources obtained from our search, as well as model rejection factors obtained recently by the AMANDA collaboration [23-25].
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Figure 7: Left panel: all-flavor neutrino flux predictions in different models of neutrino sources compared to experimental upper limits to E-2 fluxes obtained by this analysis and other experiments (see text). Also shown is the sensitivity expected for 3 live years of the new telescope NT200+ [5,40]. Right panel: Baikal experimental limits compared to two model predictions. Dotted curves: predictions from model SS [26]' SeSi [32J and SS05 [27J. Full curves: obtained experimental upper limits to spectra of the same shape. Model SS is excluded (MRF=0.25), model SeSi is not (MRF=2.12).
For an E- 2 behaviour of the neutrino spectrum and a flavor ratio Ve : v M : V T = 1 : 1 : 1, the 90% C.L. upper limit on the neutrino flux of all flavors obtained with the Baikal neutrino telescope NT200 (1038 days) is: E 2 iJ? < 8.1 x 1O-7cm-2s-1sr-1GeV. (2) For the resonant process with the resonant neutrino energy Eo = 6.3 X 10 6 GeV the model-independent limit on ve is: iJ?ve < 3.3 x 1O-20cm-2s-1sr-1GeV-l. (3) Fig. 7 (left panel) shows our upper limit on the all flavor E- 2 diffuse flux (2) as well as the model independent limit on the resonant De flux (diamond) (3). Also shown are the limits obtained by AMANDA [23-25] and MACRO [33], theoretical bounds obtained by Berezinsky (model independent (B) [34] and for an E-2 shape of the neutrino spectrum (B(E-2)) [35], by Waxman and Bahcall (WB) [36], by Mannheim et al.(MPR) [31], predictions for neutrino fluxes from topological defects (TD) [32], prediction on diffuse flux from AGNs according to Nellen et al. (NMB) [37], as well as the atmospheric conventional neutrino fluxes [38] from horizontal and vertical directions ( (v) upper and lower curves, respectively) and atmospheric prompt neutrino fluxes (vpr ) obtained by Volkova et al. [39]. The right panel of Fig. 7 shows our upper limits (solid curves) on diffuse fluxes from AGNs shaped according to the model of Stecker and Salamon (SS, SS05) [26,27] and of Semikoz and Sigl (SeSi) [32], according to Table 1.
127 Table 1: Expected number of events N m and model rejection factors for model of astrophysical neutrino sources
Model 10 '0 X eGセ@ SS Quasar [26] SS05 Quasar [27] SP u [28] SP I [28] P PI [29] M PP+PI [30] MPR [31] SeSi [32]
LIe
BAIKAL + Llr ngo%/Nm 3.08 0.81 10.00 0.25 1.00 2.5 40.18 0.062 6.75 0.37 2.19 1.14 0.86 2.86 0.63 4.0 1.18 2.12
+
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AMANDA [23-25] ngo%/Nm 0.22 0.21 1.6 0.054 0.28 1.99 1.19 2.0 -
3 Towards a km3 detector in Lake Baikal The construction of NT200+ is a first step towards a km3-scale Baikal neutrino telescope. Such a detector could be made of building blocks similar to NT200+, but with NT200 replaced by a single string, still allowing separation of highenergy neutrino induced cascades from background. It will contain a total of 1300-1700 OMs, arranged at 90-100 strings with 12-16 OMs each, and a length of 300-350 m. Interstring distance will be R::100 m. The effective volume for detection of cascades with energy above 100 TeV is 0.5-0.8 km3 . The existing NT200+ allows to verify all key elements and design principles of the km3 (Gigaton-Volume) Baikal telescope. Next milestone of the ongoing km3-telescope research and development work (R&D) will be spring 2008: installation of a "new technology" prototype string as a part of NT200+. This string will consist of 12 optical modules and a FADC based measuring system. Three issues, discussed in the remainder of this paper, have been investigated in 2007, and will permit installation of this prototype string: (1) increase of underwater (uw) data transmission bandwidth, (2) in-situ study of FADC PMpulses, (3) preliminary selection of optimal PM. More details can be found in [6].
3.1 Modernization of data acquisition system The basic goal of the NT200+ DAQ modernization is a substantial increase of uw-data rate - to allow for transmission of significant FADC data rate, and also for a more complex trigger concept (e.g. lower thresholds and topological trigger). In a first step, in 2005 a high speed data/control tcp/ip connection between the shore station and the central uw-PCs (data center) had been established (full multiplexing over a single pair of wires, with a hot spare) [4,5,40]' based on DSL-modems (FlexDSL). In 2007, the communication on the remaining segment uw-PC - string controller was upgraded using the same approach.
128
The basic elements are new string-controllers (handling TDC/ ADC-readout) with an ethernet-interface, connected by a DSL-modem to the central uw-DSL unit (3 DSL modems, max. 2 Mbps each), connected by ethernet to the uwPCs. The significant increase in uw-data rate (string to uw-PC) provided the possibility to operate the new prototype FADC system. 3.2 Prototype on a FADe based system A prototype FADC readout system was installed during the Baikal expedition 2007. It should yield input for the design of the 2008 km3 prototype string (FADC), such as: optimal sampling time window, dynamic range, achievable pulse parameter precisions, algorithms for online data handling, estimation of true bandwidth needs. These data will also be useful to decide about the basic DAQ/Triggering approach for the km3-detector: at this stage, both a complex FADC based, as well as a classical TDCI ADC approach seem feasible. The FADC prototype is located at the top of the 2nd outer string. It includes two optical modules with up-looking PM R8055, a slow control module and a FADC sphere. The FADC sphere consists of two 250 MHz FADCs, with USB connection to an embedded PCI04 computer emETX-i701, and a counter board MPCI48. The standard string trigger (2-fold channel coincidence) is used as FADC trigger. Data are transfered via local ethernet and the DSL-link of the 2nd string. Data analysis from FADC prototype is in progress.
3. 3 PM selection for the km3 prototype string Selection of the optimal PM type for the km3 telescope is a key question of detector design. Assuming similar values for time resolution and linearity range, the basic criteria of PM selection is its effective sensitivity to Cherenkov light, determined as the fraction of registered photons per photon flux unit. It depends on photocathode area, quantum efficiency, and photoelectron collection efficiency. We compared effective sensitivities of Hamamatsu R8055 (13" photocathode diameter) and XP1807 (12") with QUASAR-370 (14.6") [41], which was successfully operated in NT200 over more than 15 years. In laboratory we used blue LEDs (470 nm), located at 150 em distance from the PM. Underwater measurements are done for 2 R8055 and 2 XP1807, installed permanently as two NT200-channels, which are illuminated by the external laser calibration source [40], located 160 - 180 m away. Preliminary results of these effective PM sensitivity measurements show relatively small deviations. Smaller size (R8055, XP1807) tends to be compensated by larger photocathode sensitivities. In addition, we emphasize the advantage of a spherical shape (as QUASAR-370); we are investigating the angular integrated sensitivity looses due to various deviations from that optimum. 4 Conclusion The Baikal neutrino telescope NT200 is taking data since April 1998. The upper limit obtained for a diffuse (ve + vJ1 + vT ) flux with E- 2 shape is
129
8.1 x 1O- 7 cm- 2 s- 1 sr- 1 GeV. The limits on fast magnetic monopoles and on additional muon flux induced by WIMPs annihilation at the center of the Earth belong to the most stringent limits existing to date. The limit on a 17e flux at the resonant energy 6.3x10 6 GeV is presently the most stringent. To extend the search for diffuse extraterrestrial neutrinos with higher sensitivity, NT200 was significantly upgraded to NT200+, a detector with about 5 Mton enclosed volume, which takes data since April 2005 [5,40]. The threeyear sensitivity of NT200+ to the all-flavor neutrino flux is approximately 2 x 1O- 7 cm- 2 s- 1 sr- 1 GeV for E >10 2 TeV (shown in Fig. 7). For a km3-scale detector in Lake Baikal, R&D-activities are in progress. The NT200+ detector is, beyond its better physics sensitivity, used as an ideal testbed for critical new components. Modernization of the NT200+ DAQ allowed to install a prototype FADC PM readout. Six large area hemispherical PMs have been integrated into NT200+ (2 Photonis XP1807/12" and 4 Hamamatsu R8055/13"), to facilitate an optimal PM choice. A prototype new technology string will be installed in spring 2008 and a km3-detector Technical Design Report is planned for fall 2008. E2if? =
Acknowledgments This work was supported by the Russian Ministry of Education and Science, the German Ministry of Education and Research and the Russian Fund of Basic Research (grants 05-02-17476, 05-02-16593, 07-02-10013 and 07-02-00791), and by the Grant of President of Russia NSh-4580.2006.2. and by NATO-Grant NIG-9811707(2005). References [1] 1. Belolaptikovet al. Astropart. Phys. 7, 263 (1997). [2] V. Aynutdinov et al. Nucl. Phys. (Proc. Suppl.) B143, 335 (2005). [3] V. Aynutdinov et al. Astropart. Phys. 25, 140 (2006). [4] V. Aynutdinov et al. (Proc. of V Int. Conf. on Non-Accelerator New Physics) June 7-10 (2005) Dubna Russia. [5] V. Aynutdinov et al.(NIM) A567, 433 (2006). [6] V. Aynutdinov et al. (Proc. 30th ICRC) (icrc1084), Merida, 2007; arXiv.org: astro-ph/0710.3063. [7] V. Aynutdinov et al. (Proc. 30th ICRC) (icrc1088), Merida, 2007; arXiv.org: astro-ph/0710.3064. [8] V. Balkanov et al. Astropart. Phys. 12, 75 (1999). [9] V. Aynutdinovet al. Int. J. Mod. Phys. B20, 6932 (2005). [10] V. Balkanov et al. Nucl.Phys. (Proc.Suppl.) B91, 438 (2001). [11] V. Agrawal, T. Gaisser, P. Lipari & T. Stanev Phys. Rev. D 53, 1314 (1996). [12] M. Boliev et al. Nucl. Phys. (Proc. Suppl.) 48, 83 (1996); O. Suvorova arXiv.org: hep-ph/9911415 (1999). [13] M. Ambrosio et al. Phys. Rev. D 60, 082002 (1999).
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[14] S. Desai et al. Phys. Rev. D 70, 083523 (2004); erratum ibid D, 70, 109901 (2004). [15] K. Antipin et al. (Proc. of the First Workshop on Exotic Physics with Neutrino Telescopes) Uppsala, Sweden, Sept. 20-22, 34 (2006). [16] J. Ahrens et al. arXiv.org: astro-ph/0509330 (2005). [17] K. Antipin et al. (Proc. of the First Workshop on Exotic Physics with Neutrino Telescopes), Uppsala, Sweden, Sept. 20-22,80 (2006). [18] r. Belolaptikov et. al. [Baikal collaboration] (26th ICRC) , Salt Lake City, V.2, 340 (1999). [19] S. Orito et. al. Phys. Rev. Lett. 66, 1951 (1991). [20] M. Ambrosio et. al. [MACRO collaboration] arXiv.org: hepex/02007020 (2002). [21] P. Niessen, C. Spiering [AMANDA collaboration] (27th ICRC), Hamburg, V.4, 1496 (2001). [22] H. Wissing et al. [Ice Cube Collaboration], (Proc. 30th ICRC), Merida, 2007. [23] M. Ackermann et al. Astropart. Phys. 22, 127 (2005); Astropart. Phys. 22, 339 (2005). [24] M. Ackermann et al. Astropart. Phys. 22, 339 (2005). [25] M. Ackermann et al.Phys. Rev. D 76, 042008 (2007). [26] F. Stecker and M. Salamon Space Sci. Rev. 75, 341 (1996). [27] F. Stecker Phys. Rev. D 72, 107301 (2005). [28] A. Szabo and R. Protheroe (Proc. High Energy Neutrino Astrophysics), ed. V.J. Stenger et al., Honolulu, Hawaii (1992). [29] R. Protheroe arXiv.org:astro-ph /9612213. [30] K. Mannheim Astropart. Phys. 3, 295 (1995). [31] K. Mannheim, R. Protheroe and J. Rachen Phys. Rev. D 63, 023003 (2001). [32] D. Semikoz and G. Sigl, arXiv.org:hep-ph/0309328. [33] M. Ambrosio et al. Nucl. Phys. (Proc. Suppl.), B110, 519 (2002). [34] V. Berezinskyet al. "Astrophysics of Cosmic Rays", (Elsevier Science, North-Holland) 1990. [35] V. Berezinsky arXiv.org: astro-ph/0505220 (2005). [36] E. Waxman and J. Bahcall Phys. Rev. D 59, 023002 (1999). [37] L. Nellen, K. Mannheim and P. Biermann Phys. Rev. D, 47, 5270 (1993). [38] L. Volkova Yad. Fiz. 31, 1510 (1980). [39] L. Volkova and G. Zatsepin Phys. Lett. B462, 211 (1999). [40] V. Aynutdinov et al. (Proc. 29th Int. Cosmic Ray Conf.) August 3-10 Pune India (2005); arXiv.org: astro-ph /0507715. [41] R. Bagduev et al., (NIM) A420 (1999) 138.
NEUTRINO TELESCOPES IN THE DEEP SEA Vincenzo Flaminio a on behalf of the ANTARES Collaboration Physics Department and INFN, University of Pisa, Largo Bruno Pontecorvo 3, 56117, Pisa, Italy
Abstmct. The present is a review of current experiments performed in the deep sea in a search for 1/8 of cosmic origin. After a short recollection of the historical background, we discuss experiments that are now under construction or in the data-taking phase.
1
Introduction
Our understanding of the highly energetic processes that take place in violent stellar processes, such as Supernovae explosions, Gamma-Ray Bursts, AGNs etc. has considerably improved over the last decades, thanks to the big technological progess in the field of X and l'-ray astronomy. Apart from the intrinsic limitations that to further advances in this field are placed by the absorption of X and l'-rays in the intergalactic medium, the information that electromagnetic radiation conveys is incomplete, in that such radiation is generated mainly by high-energy electrons and photons in the dense environments of stellar objects, while there is every reason to believe that, in most of these, hadronic processes play an important role. Information on such processes can only come from VB originating from the decay of shortlived hadrons produced in high-energy nuclear interactions [1-3]. So far, the only v 8 of extraterrestrial origin detected are the Solar VB [4] and a handful of VB produced in the Supernova 1987A [5]. Many groups have actively been pursuing the task of constructing large apparatus aimed at the detection of high-energy v 8 of cosmic origin. Because of the tiny cross section, and the consequent need of very large detector masses, these detectors have adopted the Cerenkov technique using as medium either large sea or lake volumes, or the Antarctic ice. The first suggestion to use sea water as a target-detector medium for high energy cosmic v 8 is due to M.A. Markov [6]. The detection principle is sketched in figure 1. Muons produced by up-going v 8 interacting in the Earth's crust underneath the instrumented volume are detected through the Cerenkov photons they emit in water. A large photomultiplier (PMT) array records position and time of arrival of the Cerenkov photons, thus allowing a precise reconstruction of the muon direction. The range Hセ@ 1 km for a 200 GeV muon) and Cerenkov yield (about 3 x 104 photons/meter in the frequency sensitivity range of PMTs) of high energy muons in sea-water are both very large. In addition, the water transparency in this frequency range is excellent (Aab8 セ@ 50 +- 60m is the typical ae-mail: [email protected]
131
Figure 1: Schematic view of an underwater neutrino detector. The v charged-current interaction occurs in the Earth's crust underneath the detector. Cereakov photons are emitted by the. nation, while crossing the instrumented region. Each detector registers the position and arrival time of the photons, thus allowing a reconstruction of the muon direction.
value In the deep_sea);_The angle 9 between the neutrino and muon directions is: 9 < 1.5°/y/Wv (TeV): hence at high energy the ji and v directions coincide. Besides the obvious requirement of a large detector volume, an additional one derives from the Heed of screening the PMTs from undesired backgrounds, such as skylight and Cerenkov light from atmospheric y?. This requires the detector to be installed at large depths*. However, even working at large depths the latter background source may complicate the data analysis. To further reduce the effect of this background, experiments are therefore optimised for the detection of upgoing onions, generated by neutrinos that have crossed the Earth underneath. The advantages that this choice provide are achieved at a price: the Earth is not transparent to very high energy neutrinos. Indeed, for energies of the order of 103 TeV the neutrino interaction length becomes comparable to the Earth diameter. A further, unavoidable background comes from neutrinos originated in the decay of shortlived particles produced by cosmic rays in the upper atmosphere. These "atmospheric neutrinos" have relatively low energies and their contribution can. be reduced by cuts on energy. In this talk I will summarise the experiments of this kind that have been or
133
are being carried out using sea water as the medium. It is interesting to begin this review by briefly recalling the DUMAND experiment, that led the early pioneering studies and of whose experience all subsequent experiments took advantage.
2
Pioneering developments: DUM AND
The DUMAND project aimed at the installation of an underwater Cerenkov detector at a depth of about 4500 km, near the Hawaii islands. The experiment, funded in 1990, was terminated only six years later. For a comprehensive account of the historical developments and construction steps of DUM AND we refer to a paper published in 1992 by Arthur Roberts [7]. A large number of deployments were performed, some of which provided results on the atmospheric muon vertical intensity vs depth down to 5 km and on the muon angular distribution at 4 km. The DUMAND collaboration also set what at the time were the best limits on the flux of high-energy VB from AGNs. The shore station was located at the Natural Energy Laboratory of Hawaii (NELH) at Keahole Point. A cable to connect the detector to the shore station, comprising 12 single-mode optical fibers in a stainless-steel tube and surrounded by a copper sheath capable of transmitting 5 kW of electrical power, was designed and manufactured in the early 90's. In December 1993, the DUMAND collaboration successfully deployed the first major components of DUMAND, including the junction box, environmental monitoring equipment, and the shore cable, with one complete string equipped with 16" PMTs, attached to the junction box (JB). The data system could cope, with a negligible dead time, with the background rate from radioactivity in the water (primarily from natural 40 K and bioluminescence). The counting rate for a single PMT was of the order of 60 kHz, primarily due to trace 40 K in the huge volume of seawater viewed by each tube. Noise due to bioluminescence was episodic and expected to be unimportant after the array had been stationary on the ocean bottom for some time, since the light-emitting microscopic creatures are stimulated by motion. 40 K and bioluminescence contribute mainly 1 photoelectron hits distributed randomly in time over the entire array. Bioluminescence caused spikes in the singles rate which reached 100 kHz for periods on the order of seconds, but with a very low frequency of occurrence. The deployed string was used to record backgrounds and muon events. Unfortunately, an undetected flaw in one of the electrical penetrators (connectors) used for the electronics pressure vessels produced a small water leak. Seawater eventually shorted out the string controller electronics, disabling further observations after about 10 hours of operation. Recovery of the string was accomplished between 28-30 January 1994, about 44 days after it had been deployed. The developments took a long time. In retrospective it seems that this was
134
mainly caused by the lack, at least in the initial development stages, of the necessary technological means, like a reliable fiber-optical technology, pressureresistant electro-optical connectors and Remote-Operated-Vehicles (ROVs) capable to operate at depths in excess of 4000 m, for underwater connections. These became gradually available in the process of detector design, and were eventually adopted in the final setup. In mid 1996, DOE determined that further support for DUMAND-II should be terminated. The same Russian groups that contributed to DUMAND in the early stages, started an analogous enterprise under lake Baikal. This relatively small detector has operated for many years and the construction of a larger detector is now underway. Because of time constraints we shall not discuss details of this, that is not properly an "undersea" experiment. 3
Experiments in the Mediterranean sea
The construction of different prototype-detectors has been pursued over the last decades at three different locations in the Mediterranean. Chronologically, the first of these has been initiated by the NESTOR collaboration in the Ionian Sea, off the coast of Pylos, Southwestern Greece, at a depth of approximately 4000 m. The second one, NEMO is a prototype meant to be the basic building block of a km 3 detector. The chosen location is off the southern coast of Sicily, at a depth of >:;;j 3500 m. The third one, ANTARES is a medium-sized experiment (the effective area is of the same order of magnitude as the one of AMANDA [8]) now being assembled in the Mediterranean, off the southern French coast, at a depth of about 2500 m. 4
The NESTOR experiment
This has involved a large international collaboration and results obtained during the initial tests have already been published [9,10]. The chosen site is located at a distance of about 30 km Southwest of the small harbour of Methoni, at a depth of 4000 -;- 5000 m where the water quality is excellent. The detector architecture is based on what the authors call" stars". A typical star, an example of which is shown in figure 2, consists of six 16 m long arms attached to a central casing. Two optical modules (15" photomultipliers, enclosed in spherical glass housings) are attached at the end of each of the arms, one facing upwards and the other facing downwards. The electronics for each star is housed in a one-meter diameter titanium sphere within the central casing. A full NESTOR tower would consist of 12 such floors stacked vertically with a spacing od 30 m between floors. As in other undersea detectors, data and
135
power transmission is provided by electro-optical cables linking the detector to the shore station. The architecture is conceived in such a way as to avoid
Figure 2: [Left] hotmrr:~nh of a full-size NESTOR star. The test described here used a smaller detector, [right] Zenith angular distribution of atmospheric unions measured in the NESTOR prototype star in March 2003. The black dots are Me MC predictions. The inset shows the same distribution on a linear scale.
underwater operations: all connections are performed in air using dry-mating connectors before deployment. Repair operations need the recovery of the entire tower and connection cables, a formidable task for a very large detector. So far only a single smaller (5 m long arms) star has been deployed and tested for a short period in March 2003, at a depth of 3800 HI. From the total data sample collected with a four-fold coincidence trigger, 45,800 events have been selected. The resulting zenith angular distribution is shown in figure 2, where it is compared with the result of a MonteCarlo (MC) simulation of atmospheric muons, based on the Okada parameterisation [11]. The agreement is good both in shape and absolute flux. 5
The NEMO experiment
This experiment is being carried out by a large Italian collaboration. The geometry adopted is that of a series of "towers". The structure of a single tower is sketched in figure 3. It consists of 16 arms ("floors") each 18 m in length and holding a pair of 10" PMTs at its ends. The various loors are held by tensioning ropes bound to a buoy at the top. The geometry is such as to facilitate transportation and deployment, since the different loors of a given tower can by folded one on top of another, achieving a compact structure that can afterward easily be unfolded for deployment. The propsed detector geometry consists of an array of 9 x 9 such towers, interspaced by 140 m, providing an effective area of over lfern2 for energies above 10 TeV. The site
136
chosen Is located South-East of Sicily (see the inset in igure 3) at less than 80 km from shore, at a depth of 3500 m. The sea properties of this site have been studied in detail over a period of several years, and they turn out to be Ideal [12], both in terms of water properties and of biolumlnescence, A small prototype ("minitower") has been successfully deployed and tested for a few months at a somewhat shallower (« 2000 m) depth, about 20 kin away from the Catania harbour, at the end of 2006 [13]. A junction box (JB) was deployed first and connected to a pre-existing 25 km long electro-optical cable linked to a shore station. A minitower, consisting of only four "arms", each 15 m long and holding two 10" Hamamatsu PMTs at each end, was then deployed and connected to the JB. The vertical distance between arms was 40 m. Several trigger schemes were tested at the same time and a large number of events, mostly due to atmospheric muons, were recorded. Figure 3 shows a typical reconstructed muon. At the saaie time a full-scale tower is being built by the collaboration. A 100 km long electro-optical cable has beea deployed, linking the shore station, located inside the harbour area of " Portopalo di Capo Passero" with the chosen site. The building to be used as the shore laboratory for a fern,3 size detector has been acquired and is currently being equipped. Deployment of a full-sized tower is foreseen for the end of 2008.
Figure 3: [Left] The, inset shows the Capopassero site where the NEMO fern3 detector should be Installed, The two drawings illustrate the structure of the NEMO tower. [.Right] One of the first atmospheric muon tracks reconstructed In the NEMO minitower.
137
6
The ANTARES experiment
Antares is a multidiseipiiiiaxy experiment, whose main aim, of detecting neutrinos of cosmic origin, is accompanied by parallel research interests in the fields of marine biology and geophysics [15,16]. It is being carried out by a large collaboration, including Research Institutions from France, Germany, Italy, The Netherlands, Spain and Romania. Being this the experiment that has made the most impressive progress over the last couple of years, I will go here a little bit more in detail. The detector, schematically shown in figure 4, consists of 12 lines, each holding 75 10" Hamamatsu PMTs arranged in triplets (storeys) and looking downward, at an angle of 45° to the vertical. The PMTs are housed in pressure-resistant glass spheres. The separation between storeys in each line is 14.5 m, starting 100 m from the sea-floor; the distance between pairs of strings in the horizontal plane is 60-70 m. Each PMT triplet is held in place by a
Figure 4: Sketch of the Antares detector.The inset shows an indiYictaai storey, with a titanium frame holding the three glass spheres, each housing a PMT
titanium frame, as shown in the inset of figure 4, attached to a vertical electrooptical cable used for data and clock signals as well as for power transmission. Digital data transmission uses optical fibres. At the center of the frame a titanium cylinder encloses the readout/control electronics, together with compasses/tiltmeters used for geometrical positioning. Some of the storeys also house LED beacons, each containing 38 LEDs, which provide very fast pulses used for timing calibrations. For readout purposes, each group (sector) of five storeys in any given line is treated separately.
138
A laser is located at the bottom of one of the lines, while a second one is located at the bottom of the instrumentation line (see below). These provide additional means for timing calibrations. Hydrophones, attached one per sector, are used, in conjunction with sonic transmitters located at fixed locations on the sea-floor and with the compasses-tilt meters installed in the LCMs, for precise position determinations. An additional line (Instrumentation Line), equipped with instruments used to monitor other important parameters, such as temperature, pressure, salinity, light attenuation length and sound speed, is an essential component of the detector. Each line is connected, via an electronics module located at its bottom, to a JB in turn connected via a 42 km long electro-optical cable (installed in November 2001) to the shore station. All data are here collected by a computer farm, where a fast processing of events satisfying predetermined trigger requirements is performed. Precise timing is provided by a 20 MHz high accuracy on-shore clock synchronised with the GPS, distributed via the electro-optical cable and the JB to each electronics module. The expected performance of the detector has been studied in detail using MC simulations. The effective area for neutrinos reaches a maximum of :::::: 30m 2 • For v 8 at small nadir angles there is a drastic decrease at very high energies, due to absorption by the Earth. The neutrino angular resolution is dominated by electronics at high energies, where it reaches a value of :::::: 0.2 -70.3 0 • At lower energies it is dominated by the kinematics of muon production by neutrinos. Following many tests carried out over several years, the installation of the detector in its final configuration started in December 2005 and has continued in 2006 and 2007. At present five of the lines are installed and data taking is going on smoothly C. The excellent performance of the detector, both in terms of its time and space resolution has been demonstrated using data obtained with the first lines installed [14]. A very large number of triggers has been collected using the present five-line detector. These are mainly due to atmospheric muons, together with a smaller number of v 8 • Figure 5 shows the ¢ and () (zenith) distributions for atmospheric muons, compared with the MC predictions. The anisotropy in the ¢ distribution reflects the non-uniform distribution of lines in the horizontal plane. The small discrepancy present between data and MC in the () distribution is due to a still inaccurate knowledge of the angular acceptance of the optical modules d. Figure 6 shows the (z-t) plot for a reconstructed muon moving upwards (due to a neutrino interaction). The top histogram shows the measured muon angular distribution, after the application of cuts designed to reduce the contribution of atmospheric muons. The neuC At the time of writing, five additional lines and an instrumentation line have been installed and connected dThe photomultipliers look downwards at an angle of 45° in such a way as to optimise the acceptance for muons moving upwards. Their acceptance for downgoing muons is therefore more limited
139 .,-o.OO7 c - - - - - - - - - - - - - - - - - , .,ゥセ@ iMᄋ⦅ュセ@
i
N
Fセ@
0.005
Antares Data "'"'' Monte Carlo
oNPRcMセ@
;; 0.016 セ@ 0.014
1-
Antares Data .. ,"" Monte Carlo
0.01
0.00
0.00 ·150
-100
50
150 Azimuth angle [deg]
Figure 5: [Left] 4> and [Right]
(j
distributions for atmospheric muons obtained in the five-line detector.
trino sample is associated to muon events having cos () > 0; the corresponding rate is a few per day. 7
The future: conclusions
Following the pioneering DUMAND attempts and in parallel with analogous detectors now operational under the Antarctic ice, a number of undersea mediumto-large-scale experiments are under construction in the northern hemisphere. These are: NESTOR, NEMO, ANTARES. The latter, with five strings (375 PMTs) already installed e, is at present the largest running undersea experiment in the northern hemisphere. Recently the three collaborations have merged their efforts in an attempt to design and build a km 3 detector in the Mediterranean. A design study has been approved and financed by the EU [17] and work is in progress. References
M.D. Kistler and J.F. Beacom, Phys.Rev. D 74, 063007 (2006). F. W. Stecker, Phys.Rev. D 72, 107301 (2005). V. Cavasinni, D. Grasso and L. Maccione, Astrop. Phys. 26, 41(2006). For a comprehensive Review of the SSM and of the early solar neutrino experiments, see: J.N. Bahcall, "Neutrino Astrophysics", (Cambridge University Press) 1989. [5] K. Hirata et al., Phys.Rev. Lett. 58, 1490 (1987). R. M.Bionta et al., Phys.Rev. Lett. 58, 1494 (1987).
[1] [2] [3] [4]
eTen strings and 750 PMTs at the time of writing
セjエBェNャiサスv@
the plot photons on the PMT and hlsl;ogl:am shows the measured Ue!llglled to further suppress atrnospn'3r1C
DOUBLE BETA DECAY: PRESENT STATUS A.S. Barabash a
Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow, Russia Abstmct.The present status of double beta decay experiments is reviewed. The results of the most sensitive experiments, NEMO-3 and CDORICINO, are discussed. Proposals for future double beta decay experiments are considered.
1
Introduction
Interest in neutrino less double-beta decay has seen a significant renewal in recent years after evidence for neutrino oscillations was obtained from the results of atmospheric, solar, reactor and accelerator neutrino experiments. These results are impressive proof that neutrinos have a nonzero mass. The detection and study of Ov{3{3 decay may clarify the following problems of neutrino physics: (i) neutrino nature: whether the neutrino is a Dirac or a Majorana particle, (ii) absolute neutrino mass scale (a measurement or a limit on md, (iii) the type of neutrino mass hierarchy (normal, inverted, or quasidegenerate), (iv) CP violation in the lepton sector (measurement of the Majorana CP-violating phases). 2 2.1
Results of experimental investigations Two neutrino double beta decay
This decay was first recorded in 1950 in a geochemical experiment with 130Te [lJ; in 1967, it was also found for 82Se [2J. Only in 1987 2{3(2v) decay of 82Se was observed for the first time in a direct experiment [3]. Within the next few years, experiments employing counters were able to detect 2{3(2v) decay in many nuclei. In looMo [4-6], and 150Nd [7J 2{3(2v) decay to the 0+ excited state of the daughter nucleus was recorded. Also, the 2{3(2v) decay of 238U was detected in a radiochemical experiment [8], and in a geochemical experiment for the first time the ECEC process was detected in 130Ba [9J. Table 1 displays the present-day averaged and recommended values of T 1 / 2 (2v) from [10J (for looMo-100Ru(Ot) transition value is from [ll]). 2.2
Neutrinoless double beta decay
In contrast to two-neutrino decay, neutrinoless double-beta decay has not yet been observed b. ae-mail: [email protected] bThe possible exception is the result with 76Ge, published by a fraction of the HeidelbergMoscow Collaboration, Tl/2 セ@ 1.2 . 1025 Y [12J and Tl/2 セ@ 2.2· 1025 y [13J (see Table 2).
141
142 Table 1: Average and recommended Tl/2(2v) values [10). For looMo-lOORu(ot) transition value is from [11).
Isotope 48Ca 76Ge
82Se 96Zr 100Mo 100Mo-100Ru(Oi) 116Cd 128Te 130Te 150Nd 150Nd- 15 0Sm(Oi) 238U 130Ba; ECEC(2v)
1:6 .
4.3:: 10 19 (1.5 ± 0.1) . 10 21 (0.92 ± 0.07) . 1020 (2.0 ± 0.3) . 10 19 (7.1 ± 0.4) . 10 18 VNRセァZ@ . 1020 (3.0 ± 0.2) . 10 19 (2.5 ± 0.3) . 1024 (0.9 ± 0.1) . 1021 (7.8 ± 0.7) . 10 18 QNTセァZ@ . 1020 (2.0 ± 0.6) . 10 21 (2.2 ± 0.5) . 10 21
The present-day constraints on the existence of 2,B(Ov) decay are presented in Table 2 for the nuclei that are the most promising candidates. In calculating constraints on (mv), the nuclear matrix elements from QRPA calculations [1618] were used (3-d column). It is advisable to employ the calculations from these studies, because the calculations are the most thorough and take into account the most recent theoretical achievements. In column four, limits on (mv), which were obtained using the NMEs from a recent Shell Model (SM) calculations [19,20]. 3
Best present experiments
In this section the two large-scale running experiments NEMO-3 and CUORICINO are discussed. 3.1
NEMO-3 experiment !26,29j
Since June of 2002, the NEMO-3 tracking detector has operated at the Frejus Underground Laboratory (France) located at a depth of 4800 m.w.e. The detector has a cylindrical structure and consists of 20 identical sectors. A thin (about 30-60 mg/cm 2) source containing beta-decaying nuclei and having a The Moscow portion of the Collaboration does not agree with this conclusion [14) and there are others who are critical of this result [15). Thus at the present time this "positive" result is not accepted by the "2/3 decay community" and it has to be checked by new experiments.
143 Table 2: Best present results on 2/3(01/) decay (limits at 90% C.L.).
Isotope 76Ge
T 1/ 2 , Y
> 1.9.10 25
1.2. 1025 (7) セ@ 2.2 . 10 25 (7) > 1.6.10 25 > 3.10 24 > 5.8.10 23 > 4.5.10 23 > 2.1 . 1023 > 1.7.1023 セ@
130Te lOoMo 136Xe 82Se 116Cd
セ@
セ@
(mvl' eV
(mvl' eV
[16-18] < 0.22 - 0.40 0.28 - 0.51(7) 0.21 - 0.37(7) < 0.24 - 0.44 < 0.30 - 0.57 < 0.81 - 1.28 < 1.49 - 2.66 < 1.47 - 2.17 < 1.45 - 2.73
[19] < 0.76 0.96(7) 0.71(7) < 0.83 < 0.75 セ@
セ@
< 2.2 < 3.4 < 2.1
Experiment HM [21] Part of HM [12] Part of HM [13] IGEX [22] CUORICINO [23] NEMO- 3 [25] DAM A [27] NEMO-3 [25] SOLOTVINO [28]
total area of 20 m 2 and a weight of up to 10 kg was placed in the detector. The energy of the electrons is measured by plastic scintillators (1940 individual counters), while the tracks are reconstructed on the basis of information obtained in the planes of Geiger cells (6180 cells) surrounding the source on both sides. In addition, a magnetic field of strength of about 25 G parallel to the detector axis is created by a solenoid surrounding the detector. At the present time, the investigations are being performed for seven isotopes; these are looMo (6.9 kg), 82Se (0.93 kg), 1l6Cd (0.4 kg), 150Nd (37 g), 96Zr (9.4 g), 130Te (0.45 kg), and 48Ca (7 g). The corresponding limits on Tl/2(0//) and (mv} for looMo and 82Se are presented in Table 2. T 1 / 2 (2//) for all seven isotopes have been measured (see [36]). The NEMO-3 experiment is on going and new improved results will be obtained in the near future. In particular, the sensitivity of the experiment to 2;3(0//) decay of lOoMo will be on the level of rv 2 . 10 24 y. This in turn means the sensitivity to (mv} will be on the level of rv 0.4 - 0.7 eV. 3.2
CUORICINO [24]
This program is the first stage of the larger CUORE experiment (see section 4). The experiment is running at the Gran Sasso Underground Laboratory. The detector consists of 62 individual low-temperature natTe02 crystals, their total weight being 40.7 kg. The energy resolution is 7.5-9.6 keY at an energy of 2.6 MeV. The experiment has been running since March of 2003. The corresponding limits on Tl/2(0//) and (mvl for 130Te are presented in Table 2. The sensitivity of the experiment to 2;3(0//) decay of 130Te will be on the
144
level of '" 5 . 1024 for 3 y of measurement. This in turn means the sensitivity to (my) is on the level of'" 0.2 - 0.6 eV. 4
Planned experiments
In this section, main parameters of five promising experiments which can be realized within the next five to ten years are presented. The estimation of the sensitivity in all experiments to the (my) is made using NMEs from [16-19]. Table 3: Five most developed and promising projects.
5
Experiment
Isotope
CUORE [30] GERDA [31]
130Te 76Ge
MAJORANA [32,33] EXO [34]
76Ge 130Xe
SuperNEMO [35,36]
82S e 150Nd
Mass of isotope, kg 200 40 1000 60 1000 200 1000 100-200
Sensitivity T 1L2, Y 2.1. 1026 2.10 26 6.10 27 2.10 26 6.10 27 6.4.10 25 2.10 27 (1 - 2) . 1026
Sensitivity (my), meV 35-90 70-230 10-40 70-230 10-40 120-220 20-40 45-110
Status accepted accepted R&D R&D R&D accepted R&D R&D
Conclusion
In conclusion, two-neutrino double-beta decay has so far been recorded for ten nuclei (48 Ca, 76Ge, 82Se , 96Z r , lOoMo, 116Cd, 128Te, 130Te, 150Nd, 238U). In addition, the 2f3(2v) decay of lOoMo and 150Nd to 0+ excited state of the daughter nucleus has been observed and the ECEC(2v) process in 130Ba was recorded. Neutrinoless double-beta decay has not yet been confirmed. There is a conservative limit on the effective value of the Majorana neutrino mass at the level of 0.75 eV. Within the next few years, the sensitivity to the neutrino mass in the CUORICINO and NEMO-3 experiments will be improved to become about 0.2 to 0.6 eV with measurements of 130Te and lOoMo. The next-generation experiments, where the mass of the isotopes being studied will be as grand as 100 to 1000 kg, will have started within three to five years. In all probability, they will make it possible to reach the sensitivity to the neutrino mass at a level of 0.1 to 0.01 eV.
145
References
[1] [2] [3] [4] [5] [6] [7] [8]
M.G. Inghram, J.H. Reynolds, Phys. Rev. 78,822 (1950). T. Kirsten, W. Gentner, O.A. Schaeffer, Z. Phys. 202, 273 (1967). S.R. Elliott, A.A. Hahn, M.K. Moe, Phys. Rev. Lett. 59, 2020 (1987). A.S. Barabash et al., Phys. Lett. B 345, 408 (1995). A.S. Barabash et al., Phys. At. Nucl. 62, 2039 (1999). L. De Braeckeleer et al., Phys. Rev. Lett. 86,3510 (2001). A.S. Barabash et al., JETP Lett. 79, 10 (2004). A.L. Turkevich, T.E. Economou and G.A. Cowan, Phys. Rev. Lett. 67, 3211 (1991). [9] A.P. Meshik et al., Phys. Rev. C 64, 035205 (2001). [10] A.S. Barabash et al., Czech.J. Phys. 56,437 (2006). [11] A.S. Barabash, AlP Conf. Proc. 942: 8 (2007). [12] H.V. Klapdor-Kleingrothaus et al., Phys. Lett. B 586, 198 (2004). [13] H.V. Klapdor-Kleingrothaus and LV. Krivosheina. Mod. Phys. Lett. A 21, 1547 (2006). [14] A.M. Bakalyarov et al., Phys. Part. Nucl. Lett. 2, 77 (2005); hepex/0309016. [15] A. Strumia and F. Vissani, Nucl. Phys. B 726, 294 (2005). [16] V. Rodin et al., Nucl. Phys. A 793, 213 (2007). [17] M. Kortelainen and J. Suhonen, Phys. Rev. C 75, 051303(R) (2007). [18] M. Kortelainen and J. Suhonen, Phys. Rev. C 76,024315 (2007). [19] E. Caurier et al., nucl-th/0709.2137. [20] E. Caurier et al., nucl-th/0709.0277. [21] H.V. Klapdor-Kleingrothaus et al., Eur. Phys. J. A 12, 147 (2001). [22] C.E. Aalseth et al., Phys. Rev. C 65, 09007 (2002). [23] A. Giuliani (CUORICINO Collaboration), report at TAUP'07 (Sendai, 11-13 September, 2007). [24] C. Arnaboldi et al., Phys. Rev. Lett. 95, 142501 (2005). [25] A.S. Barabash (NEMO Collaboration), hep-ex/0610025. [26] R. Arnold et al., Phys. Rev. Lett. 95, 182302 (2005). [27] R. Bernabei et al., Phys. Lett. B 546, 23 (2002). [28] F.A. Danevich et al., Phys. Rev. C 67, 035501 (2003). [29] R. Arnold et al., Nucl. Instr. Meth. A 536, 79 (2005). [30] C. Arnaboldi et al., Nucl. Instr. Meth. A 518, 775 (2004). [31] 1. Abt et al., hep-ex/0404039. [32] Majorana White Paper, nucl-ex/0311013. [33] C.E. Aalseth et al., Nucl. Phys. B (Pmc. Suppl.) 138, 217 (2005). [34] M. Danilovet al., Phys. Lett. B 480, 12 (2000). [35] A.S. Barabash, Czech. J. Phys. 52,575 (2002). [36] S. Soldner-Rembold (NEMO Collaboration), hep-ex/0710.4156.
BETA-BEAMS C. Volpe a
Institut de Physique Nucleaire Orsay, F-91406 Orsay cedex, FRANCE Abstract. Beta-beams is a new concept for the production of intense and pure neutrino beams. It is at the basis of a proposed neutrino facility, whose main goal is to explore the possible existence of CP violation in the lepton sector. Here we briefly review the original scenario and the low energy beta-beam. This option would offer a unique opportunity to perform neutrino interaction studies of interest for particle physics, astrophysics and nuclear physics. Other proposed scenarios for the search of CP violation are mentioned.
1
Introduction
The observations made by the Super-Kamiokande [1], the K2K [2], the SNO [3] and the KAMLAND [4] experiments have brought a breakthrough in the field of neutrino physics. The longstanding puzzles of the solar neutrino deficit [5] and of the atmospheric anomaly have been clarified: the expected fluxes are reduced due to the neutrino oscillation phenomenon, i.e. the change in flavour that neutrinos undergo while traveling [6]. The overall picture is now also confirmed by the recent mini-BOONE result [7]. Neutrino oscillations imply that neutrinos are massive particles and represent the first direct experimental evidence for physics beyond the Standard Model. Understanding the mechanism for generating the neutrino masses and their small values is clearly a fundamental question, that needs to be understood. On the other hand, the presently known (as well as unknown) neutrino properties have important implications for other domains of physics as well, among which astrophysics, e.g. for our comprehension of processes like the nucleosynthesis of heavy elements, and cosmology. An impressive progress has been achieved in our knowledge of neutrino properties. Most of the parameters of the Maki-Nakagawa-Sakata-Pontecorvo (MNSP) unitary matrix [8], relating the neutrino flavor to the mass basis, are nowadays determined, except the third neutrino mixing angle, usually called 813 . However, this matrix might be complex, meaning there might be (one or more) phases. A non-zero Dirac phase introduces a difference between neutrino and anti-neutrino oscillations and implies the breaking of the CP symmetry in the lepton sector. Knowing its value might require the availability of very intense neutrino beams in next-generation accelerator neutrino experiments, namely super-beams, neutrino factories or beta-beams. Besides representing a crucial discovery, the observation of a non-zero phase might help unraveling the asymmetry between matter and anti-matter in the Universe and have an impact in astrophysics, e.g. for core-collapse supernova physics [9]. ae-mail: [email protected]
146
147
Zucchelli has first proposed the idea of producing electron (anti)neutrino beams using the beta-decay of boosted radioactive ions: the "beta-beam" [lOJ. It has three main advantages: well-known fluxes, purity (in flavour) and collimation. This simple idea exploits major developments in the field of nuclear physics, where radioactive ion beam facilities under study such as the european EURISOL project are expected to reach ion intensities of 10 11 - 13 per second. A feasibility study of the original scenario is ongoing (2005-2009) within the EURISOL Design Study (DS) financed by the European Community. At present, various beta-beam scenarios can be found in the literature, depending on the ion acceleration. They are usually classified following the value of the Lorentz I boost factor, as low energy h = 6-15) [11-21,21-24]' original h セ@ 60 - 100) [10,25-30], medium h of several hundreds) and high-energy h of the order of thousands) [31-35]. (For a review of all scenarios see [36].) An extensive investigation of the corresponding physics potential is being performed and new ideas keep being proposed. For example, a radioactive ion beam production method is discussed in [37] and will be investigate within the new "EuroNU" DS. Thanks to this method two new ions 8B and 8Li are being considered as candidate emitters, while the previous literature is mainly focussed on 6He and 18Ne. The corresponding sensitivity is currently under study (see e.g. [38]). 2
The original scenario
In the original scenario [10]' the ions are produced, collected, accelerated up to several tens GeV /nucleon - after injection in the Proton Synchrotron and Super Proton Synchrotron accelerators at CERN - and stored in a storage ring of 7.5 km (2.5 km) total length (straight sections). The neutrino beam produced by the decaying ions point to a large water Cerenkov detector [39] (about 20 times Super-Kamiokande), located at the (upgraded) FrEljus Underground Laboratory, in order to study CP violation, through a comparison of lie -+ 11/-1 and De -+ D/-I oscillations. This facility is based on reasonable extrapolation of existing technologies and exploits already existing accelerator infrastructure to reduce cost. Other technologies are being considered for the detector as well [40J. A first feasibility study is performed in [41]. The choice of the candidate emitter has to meet several criteria, including a high intensity achievable at production and a not too short/long half-life. The ion acceleration window is determined by a compromise between having the I factor as high as possible, to profit of larger cross sections and better focusing of the beam on one hand, and keeping it as low as possible to minimize the single pion background and better match the CP odd terms on the other hand. The signal corresponds to the muons produced by 11/-1 charged-current events in water, mainly via quasi-elastic interactions at these energies. Such events are
148 Table 1: Number of events expected after 10 years, for a beta-beam produced at CERN and sent to a 440 kton water Cerenkov detector located at an (upgraded) Frejus Underground Laboratory, at 130 km distance. The results correspond to ve (left) and Ve (right). The different 'Y values are chosen to make the ions circulate together in the ring [26] 18 Ne
6He
(r CC events (no oscillation) Oscillated (sin228l3 = 0.12, 15 Oscillated (15 = 90° ,8 13 = 3°) Beam background Detector backgrounds
= 0)
= 60) 19710 612 44
o 1
(r
= 100) 144784 5130 529 0 397
selected by requiring a single-ring event, with the same identification algorithms used by the Super-Kamiokande experiment, and by the detection of the electron from the muon decay. At such energies the energy resolution is very poor due to the Fermi motion and other nuclear effects. For these reasons, a CP violation search with 'Y = 60 - 100 is based on a counting experiment only. The beta-beam has no intrinsic backgrounds, contrary to conventional sources. However, inefficiencies in particle identification, such as single-pion production in neutral-current Ve (ve) interactions, electrons (positrons) misidentified as muons, as well as external sources, like atmospheric neutrino interactions, can produce backgrounds. The background coming from single pion production has a threshold at about 450 MeV, therefore giving no contribution for 'Y < 55. Standard algorithms for particle identification in water Cerenkov detectors are quite efficient in suppressing the fake signal coming from electrons (positrons) misidentified as muons. Concerning the atmospheric neutrino interactions, estimated to be of about 50/kton/yr, this important background is reduced to 1 event/440 kton/yr by requiring a time bunch length for the ions of 10 ns. The expected events from [26] are shown in Table 1, as an example. The discovery potential is analyzed in [10,25-30]. A detailed study of 'Y = 100 option is made for example in [29] based on the GLoBES software [42], including correlations and degeneracies and using atmospheric data in the analysis [33]. The fluxes are shown in Figure 1. Figure 2 shows the CP discovery reach as an example of the sensitivity that can be reached running the ions around 'Y = 100.
3
Low energy beta-beams
A low energy beta-beam facility producing neutrino beams in the 100 MeV energy range has been first proposed in [11]. Figure 3 shows the corresponding fluxes. The broad physics potential of such a facility, currently being analyzed, covers:
149 t..
セ@ BGセ@
x l 0 7 e - - - -_ _ _ _ _ _ _セ@ 8000
-
o
.€ ;>
2n 30 discovery of CP violation:
!:J.i (liep = 0, n):= 9
SPL カセ@
7000
','" Q)
e:;;
2,Qx10·
s
20
40
60
80
100
Ey (MeV)
Figure 3: Anti-neutrino fluxes from the decay of 6He ions boosted at "! = 6 (dot-dashed line),,,! = 10 (dotted line) and,,! = 14 (dashed line). The full line presents the Michel spectrum for neutrinos from muon decay-at-rest.
I'"
03.4
3.5
4.0
Figure 4: eve Test : セxR@ obtained from the angular distribution of electron anti-neutrinos on proton scattering in a water Cerenkov detector in the cases when the statistical error only (solid), with 2% (dashed), 5% (dash-dotted) and 10% (dotted) systematic errors. The 1
(15)
.
i
Here II = Fill' Fill' is the first invariant of the tensor Fill'. Let us discuss the physical meaning of the results obtained. For this purpose we shall consider vector and axial currents constructed with help of solution
(8):
Vil セ@
= セHxィャjNヲI@
= qll/l,
All
= セHxィULiャjNヲI@
= (0
セsiャL@
(16)
q
S/1 = -Sfp(SoStp)
+ [st +Sfp(SoStp)] cos 2B- セ・ャGpaアsoエ@
m
B = (Nx)J(cpq)2 - cp 2m 2/m.
sin 2B,
(17)
セM
Thus, solution (8) which is a linear combination of solutions (11) describes a spin-coherent state of neutrino, propagating with the velocity v = q/ qO . In these states neutrino spin rotation takes place. Therefore, neutrino state with rotating spin is a pure state. Existence of such solutions is the direct consequence of the neutrino state description in terms of kinetic momentum. It should be stressed that as the result of calculations we obtained the complete system of neutrino wave functions, which show spin rotation properties. Introduce a flight length L of a particle and an oscillations length Lose, using the relation B = 7r L / Lose. Since the scalar product (N x) = T can be interpreted as the proper time of a particle, then the oscillation length is defined as
192
In this formula we use gaussian units and restore the neutrino magnetic moment /10·
Hence if as a result of a certain process a neutrino arises with polarization (0, (the spin vector ( can be expressed in terms of the four-vector SJ-I components as ( = S - qSO /(qO + m)), after travelling the distance L the probability for the neutrino to have polarization -(0 is equal to 2
W s! = [(0 x (tp] sin 2 (7fL/Los c). (19) Consequently, if the condition (o(tp) = 0 is fulfilled, this probability can become unity, i.e. a resonance takes place. In this way we obtained the exact solutions of the Dirac-Pauli equation for neutrino in dense matter and electromagnetic field. It was demonstrated that if the neutrino production occurs in the presence of an external field and a dense matter, then its spin orientation is characterized by the vector Sip' Due to the time-energy uncertainty relation the considered states of neutrino can be generated only when the linear size of the area occupied by the electromagnetic field and the matter is comparable with the process formation length. This length is of the order of the oscillations length. Acknowledgments The authors are grateful to A.V. Borisov, O.F. Dorofeev and V.Ch. Zhukovsky for helpful discussions. This work was supported in part by the grant of President of Russian Federation for leading scientific schools (Grant SS 5332.2006.2) . References
[1] [2] [3] [4]
[5] [6] [7] [8] [9] [10] [11] [12]
B.W. Lee, R.E. Shrock, Phys. Rev. D 16, 1444 (1977). K. Fujikawa, R.E. Shrock Phys. Rev. Lett. 45,963 (1980). J. Schechter, J.W.F. Valle, Phys. Rev. D 24, 1883 (1981). M.B. Voloshin, M.I. Vysotsky, L.B. Okun, Zh. Eksp. Teor. Fiz. 91, 754 (1986); C.-S. Lim, W.J. Marciano, Phys. Rev. D 37, 1368 (1988); E.Kh. Akhmedov, Phys. Lett. B 213, 64 (1988). A.V. Borisov, A.I. Ternov, V.Ch. Zhukovsky, Izv. Vyssh. Uchebn. Zaved. Fiz. 31, No 3, 64 (1988); M. Dvornikov arXiv:0708.2328 [hep-ph] (2007). A.Yu. Smirnov, Phys. Lett. B 260, 161 (1991); E.Kh. Akhmedov, S.T. Petcov, A.Yu. Smirnov, Phys. Rev. D 48, 2167 (1993). L. Wolfenstein, Phys. Rev. D 17, 2369 (1978). S.P. Mikheyev, A.Yu. Smirnov, Yad. Fiz. 42, 1441 (1985). A.E. Lobanov, A.I. Studenikin, Phys. Lett. B 515, 94 (2001). A.E. Lobanov, O.S. Pavlova, Vestn. MGU. Fiz. Astron. 40, No 4, 3 (1999); A.E. Lobanov, J. Phys. A: Math. Gen. 39, 7517 (2006). A.E. Lobanov, Phys. Lett. B 619, 136 (2005). V.Ch. Zhukovsky, A.E. Lobanov, E.M. Murchikova, Phys. Rev. D 73, 065016 (2006).
PLASMA INDUCED NEUTRINO SPIN FLIP VIA THE NEUTRINO MAGNETIC MOMENT A.Kuznetsov a, N.Mikheev b Yaroslavl State P. G. Demidov University, Sovietskaya 14, 150000 Yaroslavl, Russia Abstract. The neutrino spin flip radiative conversion processes ilL -> IIR + 'Y. and + 'Y. -> IIR in medium are considered. It is shown in part that an analysis of the so-called spin light of neutrino without a complete taking account of both the neutrino and the photon dispersion in medium is physically inconsistent. ilL
1
Introduction
The most important event in neutrino physics of the last decades was the solving of the Solar neutrino problem. The Sun appeared in this case as a natural laboratory for investigations of neutrino properties. There exists a number of natural laboratories, the supernova explosions, where gigantic neutrino fluxes define in fact the process energetics. It means that microscopic neutrino characteristics, such as the neutrino magnetic moment, etc., would have a critical impact on macroscopic properties of these astrophysical events. One of the processes caused by the photon interaction with the neutrino magnetic moment, which could play an important role in astrophysics, is the radiative neutrino spin flip transition VL --t VRf' The process can be kinematically allowed in medium due to its influence on the photon dispersion, w = Iklln (here n =1= 1 is the refractive index), when the medium provides the condition n > 1. In this case the effective photon mass squared is negative, m; == q2 < O. This corresponds to the well-known effect of the neutrino Cherenkov radiation [1]. There exists also such a well-known subtle effect as the additional energy W acquired by a left-handed neutrino in plasma. This additional energy was considered in the series of papers by Studenikin et al. [2] as a new kinematical possibility to allow the radiative neutrino transition VL --t VRf' The effect was called the "spin light of neutrino". For some reason, the photon dispersion in medium providing in part the photon effective mass, was ignored in these papers. However, it is evident that a kinematical analysis based on the additional neutrino energy in plasma (caused by the weak forces) when the plasma influence on the photon dispersion (caused by electromagnetic forces) is ignored, cannot be considered as a physical approach. In this paper, we perform a consistent analysis of the radiative neutrino spin flip transition in medium, when its influence both on the photon and neutrino dispersion is taken into account. a e-mail:
[email protected] be-mail: [email protected]
193
194
2
Cherenkov process
VL ----) VR'Y
and its crossing
VL'Y ----) VR
Let us start from the Cherenkov process of the photon creation by neutrino, VL ----) VR'Y, which should be appended by the crossed process of the photon absorption VL'Y ----) VR. At this stage we neglect the additional left-handed neutrino energy W, which will be inserted below. For the VL ----) VR conversion width one obtains by the standard way:
r tot
VL-tl/R
where CrA) is the photon polarization vector, j"" is the Fourier transform of the neutrino magnetic moment current, pOI. = (E,p), p'OI. = (E',p') and qOl. = (w, k) are the four-momenta of the initial and final neutrinos and photon, respectively, A = t, C mean transversal and longitudinal photon polarizations, f'Y(w) = (e w / T _1)-1 is the Bose-Einstein photon distribution function, and zセaI@ = (1 - 8II(A)/8w 2)-1 is the photon wave-function renormalization. The functions II(A) , defining the photon dispersion law:
(2) CrA) = II(A) C(A)OI.' The width イセエMKvr@ can be rewritten to another form. Let us introduce the energy transferred from neutrino: E - E' = qo, which is expressed via the photon energy w(k) as qo = ±w(k). Then 00)
pr,a 2.4 X 10 16 y) and of 1.53 Eu into 149Pm (T1/ 2 > 1.1 X 10 16 y) was achieved in a preliminary measurement using a Li6Eu(B03h crystal (mass::: 2.72 g) at LNGS [1]. In a second measurement, a low background CaF 2 (Eu) crystal scintillator 3"(2) x 1" (mass of 370 g), doped by Europium, was used to search for the a activity of 151 Eu [2]. The concentration of Eu in the crystal was determined with the help of the ICP Mass Spectrometry analysis: (0.4 ± 0.1)%. The detector was installed in the DAMA/R&D set-up operative at LNGS at a depth of 3600 m.w.e. The energy scale and resolution of the CaF 2 (Eu) detector for, quanta were measured with standard, sources and the response of the detector to a particles was studied with a collimated 241 Am a source - by using different sets of absorbers - from 1 MeV up to 5.25 MeV (see Fig. 1a). To discriminate events from a decays inside the crystal from the ,(/3) background, the optimal filter method was applied and the energy dependence of the shape indicators (SI) was measured. The low energy part of the background spectrum measured with the CaF 2 (Eu) crystal scintillator during 7426 h is shown in Fig.lb. There is a peculiarity in the spectrum at the energy near 250 keV 225
226
セ@
.£ 0.25
"ii 0.2
0.15
500
o
10 Energy of (.( particles (MeV)
a)
b)
-1 Qセ@
200
__セ@ 2jO
__セ@ 300
____セ@ 350
400
__セ@ 450
;00
Energy (keVl
Figure 1: Left Energy dependence of the 0:/13 ratio for the CaF2(Eu) scintillation detector. Measurements with 241 Am source using different sets of absorbers (mylar or few mm of air in some cases) are shown by circles; points shown by triangles have been obtained from the identified 0: activity in the background data. Right: Low energy part of the background spectrum measured during 7426 h in the low background set-up with the CaF2(Eu) scintillator (crosses). The peculiarity on the left of the 1478m peak can be attributed to the 0: decay of 151 Eu with the half-life Tl/2 = 5 X 10 18 y. The 0: nature of the two peaks is further supported by the pulse shape discrimination analysis; see discussion on the bottom lines given in ref. [2].
in agreement with the expected energy of the 1.51 Eu alpha decay - which gives an indication on the existence of this process. Therefore, the half-life of 151 Eu relatively to the 0: decay to the ground state of 147 Pm has been evaluated to be: Tf;2(g.S. -+ g.s.) = 5!j1 X 10 18 y, or, in a more conservative approach: Tfo,(g.s. -+ g.s.) 2: 1.7 X 10 18 Y at 68(;70 C.L. [2]. In addition, for the decay of 15 1Eu to the first excited (Ei/2+,Eexc =fll keY) 17 level of 147 Pm a limit has also been obtained: tセOBRHァNX@ -> .5/2+) 2: 6 X lO y at 68%C.L. Theoretical half-lifes for 151 Eu 0: decay calculated in different model frameworks are in the range of (0.3-3.6) x 10 18 y; in particular, the measured value of half-life of 151 Eu is well in agreement with the calculations of [3]. 2
Measurement of 2/32v decay of 100Mo to the
at level of 100Ru [4]
The meAsuReMent of twO-NeutrIno 2/3 decAy of 100Mo to the first excited level of lOoRu (ARMONIA) consists of a Mo sample of:::: 1 kg enriched in 100Mo at 99.5% in form of metallic powder installed in the four low-background HP Ge detectors (about 225 cm3 each, all mounted in one cryostat) facility located at LNGS. The aim of this high sensitivity experiment is to measure the 2/32v decay of 100Mo to the first excited level of lOoRu [E(Ot) = 1130 ..5 keV] either to confirm positive results reported in [5] (with T1/2 in the range around 6 - 9 X 1020 y) or to confirm previous higher limit value of ref. [6] (T1/ 2 > 1.2 X 10 21 Y at 90% C.L.). Preliminary data have been collected deep underground at LNGS during 1927 h (see Fig. 2). Two 'Y of 590.8 keY and 539.6 keY respectively are expected in the level de-excitation of the lOoRu. The measured energy distribution in the range of 500-600 keY is reported in Fig. 2 and compared
Or
ot
at
Figure 2: Spectrum of 100 Mo sample (mass of 1009 g) measured with 4 HP Ge detectors setup at LNGS during 192? h in the range of 600-600 keV. Shaded area is background spectrum (without 100 Mo sample) normalised to the same time of measurements. Peaks at 583 keV and 511 keV are related with 20®Tl decay and the positron annihilation process, respectively.
with the background spectrum measured without the 100Mo sample (shaded area). Note that peaks at 583 keV and 511 keV are related with 2O8T1 decay and the positron annihilation process, respectively. A modest peak structure seems to be present - but at very low C.L. - around 540 keV, where one 7 searched for is expected. If this would be ascribed to the decay searched for, one gets: T1/2 = 3 x 1020 y. However, no significant statistical evidence for the peak at the energy of 591 keV is found at present and a limit on the half-life can be derived: T1/2 > 6 x 1020 y at 90% C.L.. These measurements have shown that AR.M0NIA is entering in the sensitivity region of interest. New data taking with further purified sample and larger exposure is in progress, 3
Search for 2/3 processes in
64
Zn with a ZNWO4 scintillator [7].
Zn is one of the few exceptions among 20+ nuclei having big natural isotopic abundance (48.268%); the mass difference between 64Zn and 64Ni nuclei is 1095.7(0.7) keV and, therefore, double electron capture (2s), and electron capture with emission of positron (s[3+) are energetically allowed. A low background ZnWO4 crystal scintillator (mass of 117 g) has been installed deep underground in the low background DAMA/R&D set-up at the LNGS for the investigation of double beta processes in 64Zn with higher sensitivity. The energy scale and resolution of the Z11WO4 detector for 7 quanta were measured with 22Na, 133Ba, 137Os, 228Th and 241Am sources. The energy spectrum measured during 1902 h is presented in Fig. 3. Comparing the simulated response functions for different 2/3 processes in 64 Zn with the experimental energy distribution accumulated with the ZnWO.4 crystal we did not find the peculiarities expected in the spectra. Therefore, lower half-life limits can be set for the 2/3 processes in decay 64Zn — 64Ni at 90% C.L. (see table 1) improving the previous results; moreover, the positive
64
22B
400
lOO
6()O
ROO
Energy (keV)
Instr. £.1 Meth. A A 789
44
to appear on
Rad-i.at. I8ot. 46 (1995) 455. KEK Pmc. 6 (2003) 205. arXiv: 0707.2756vl [nucl-exJ. H. Kiel et Phys. A 723 (2003) 499. Danevich et al., Nucl. Instr. & Meth. A 544
ANISOTROPY OF DARK MATTER ANNIHILATION AND REMNANTS OF DARK MATTER CLUMPS IN THE GALAXY V.Berezinskya INFN, Laboratori Nazionali del Gran Sasso, 1-67010 Assergi (AQ), Italy V .Dokuchaev b, Yu.Eroshenko C Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia Abstract.A mass function of small-scale dark matter clumps is calculated by taking into account the tidal destruction of clumps at early stages of structure formation. The surviving clumps can be disrupted further in the Galaxy by tidal interactions with stars. A corresponding annihilation of dark matter particles in clumps produces the anisotropic gamma-ray signal on the level '" 9% with respect to the Galaxy plane. It is demonstrated that a substantial fraction of clump remnants may survive the tidal destruction during the lifetime of the Galaxy if a clump core radius is rather small. The dense part of clump core produces the dominating input into the annihilation signal from a single clump. For this reason the survived dense remnants of tidally destructed dark matter clumps may provide the major contribution to annihilation signal from the Galactic halo.
1
Dark matter clumps
About 30% of mass of the Universe is in a form of cold dark matter (DM), but the nature of DM particles is still unknown. The cold DM component is gravitationally unstable and forms the gravitationally bounded clumpy structures from the scale of superclusters of galaxies and down to very small clumps of DM. The cutoff of the mass spectrum, Mmin is determined by the collisional and collisionless damping processes and typical values Mmin rv (10- 8 - 1O-6)M8 for neutralino DM. Due to uncertainties in the SUSY parameters, a numerical value of Mmin is not exactly predicted. Theoretical study of DM clumps are important for understanding the properties of DM particles, because annihilation of DM particles in small dense clumps may result in observable signals. The cosmological formation and evolution in early Universe and properties of small-scale DM clumps have been studied in many works [1-9]. Only very small fraction of these clumps survives the early stage of tidal destruction during the hierarchial clustering. Nevertheless these survived clumps will provide the major contribution to the annihilation signal in the Galaxy [9]. One of the unresolved problem of DM clumps is a value of the central density or core radius. Numerical simulations give a nearly power density profile of DM clumps. Both the Navarro-Frenk-White and Moore profiles give formally a divergent density in the clump center. A theoretical modelling of the clump ae-mail: [email protected] be-mail: [email protected] ce-mail: [email protected]
229
230
formation [10] predicts a power-law profile of the internal density of clumps
Pint(r)
=
(r )-f3 '
3 - (J _ -3- P R
(1)
where 15 and R are the mean internal density and a radius of clump, respectively, 1.8 - 2 and Pint(r) = 0 at r > R. A near isothermal power-law profile (1) with (J セ@ 2 has been recently obtained in numerical simulations of small-scale clump formation [11].
(J セ@
2
Cosmological distribution function of clumps
The first gravitationally bound objects in the Universe are the DM clumps of the minimum mass Mmin. In the case of the Harrison-Zeldovich spectrum of primordial fluctuations with CMB normalization the first small-scale DM clumps are formed at redshift z rv 60 (for 20' fluctuations) with a mean density 7 x 10- 22 g cm- 3 , virial radius 6 x 10- 3 pc and internal velocity dispersion 80 cm s-l respectively. The clumps of larger scales are formed later. The internal energy increase after a single tidal shock experienced by the clump captured into larger host clump is t::.E セ@ (47r/3)'YlGphMR2, where Ph is the density of a host and the numerical factor ,1 rv 1. Let us denote by ,2 the number of tidal shocks per dynamical time tdyn' The corresponding rate of internal energy growth for a clump is E = '2t::.E/tdyn. A clump is destroyed if its internal energy increase exceeds a total energy lEI セ@ G M2 /2R. For a typical time T = T(p, Ph) of the tidal destruction of a small-scale clump with density P we obtain:
T -l( p, Ph ) -_
E - 4'1,2 Gl/2 Ph3/2 P-1 . lEI rv
(2)
It turns out that a resulting mass function of small-scale clumps depends rather weakly on the value of product ,1,2. During its lifetime a small-scale clump can stay in many host clumps of larger mass. After tidal disruption of the first lightest host, a small-scale clump becomes a constituent part of a larger one, etc. The process of hierarchical transition of a small-scale clump from one host to another occurs almost continuously in time up to the final host formation, where the tidal interaction becomes inefficient. The probability of clump survival, determined as a fraction of the clumps with mass M surviving the tidal destruction in hierarchical clustering, is given by the exponential function e- J with (3)
Here t::.th is a difference of formation times th for two successive hosts, and summation goes over all clumps of intermediate mass-scales, which successively
231
host the considered small-scale clump of a mass M. Changing the summation by integration in (3) we obtain
(4) where 'Y ::: 14(r1/2/3), and t, h, tt, p, Pl are respectively the formation times and internal densities of the considered clump and of its first and last hosts. One may see from Eq. (4) that the first host provides a major contribution to the tidal destruction of the considered small-scale clump, especially if the first host density Pl is close to p, and consequently e- J « 1. Finally using the Press-Schechter formalism we obtained in [12] the following distribution function of clumps (mass fraction):
c dM d rv lJdlJ -V 2 /2f ( )dlogO"eq(M) dM ." M lJ - J27r e 1 'Y dM '
(5)
where O"eq(M) is a r.m.s. fluctuation on a mass-scale M at the time of matterradiation equality, lJ is the peak high and one may use h (r) ::: 0.2 - 0.3. Integrating Eq. (5) over lJ, we obtain eint
dM dM M ::: 0.02(n + 3) M .
(6)
An effective power-law index n in Eq. (6) is determined as n = -3(1 + 28logO"eq(M)/8log M) and depends very weakly on M. The simple M- 1 shape of the mass function (6) is in a very good agreement with the corresponding numerical simulations [11], but our normalization factor is a two times smaller.
3
Tidal destruction of clumps
Crossing the Galactic disk, a DM clump can be tidally destructed by the collective gravitational field of stars in the disk. This phenomenon is similar to the destruction of globular clusters. The kinetic energy gain of a DM particle with respect to the center of clump after one crossing of the Galactic disk is [13]
(7) where m is a constituent DM particle mass, l1z is a vertical distance (orthogonal to the disk plane) of a DM particle with respect to the center of clump, vz,c is a vertical velocity of clump with respect to the disk plane at the moment of disk crossing, gm(r) is gravitational acceleration near the disk plane and we use an
232 exponential model for a surface density of disk. As a representative example we consider the isothermal internal density profile of DM clumps. We used the adiabatic correction in Weinberg's form A(a) = (1 + a 2 )-3/2 [14], where the adiabatic parameter a = WTd with W is an orbital frequency of DM particle in the clump, T is an effective duration of gravitational tidal shock. In [12J we describe a gradual mass loss of small-scale DM clumps assuming that only the outer layers of clumps are involved and influenced by the tidal stripping. Additionally we assume that inner layers of a clump are not affected by tidal forces. In this approximation we calculate a continues diminishing of the clump mass and radius during the successive galactic disk crossings and encounters with the stars. As a criterium of a clump destruction we accept now the approaching of the radius of tidally stripped clump down to the core radius. By using the hypothesis of a tidal stripping of outer layers of a DM clump we see that a tidal energy gain Jc causes the stripping of particles with energies in the range -Jc < c < O. A corresponding variation of density at radius r is
Jp(r)
5 2
= 2 / 7r
J° Vc -
'Ij;(r) fcl(c) dc,
(8)
-/it:
where fcl(c) is the distribution of particles inside a clump over energy (in dimensionless variables). A resulting total mass loss by DM clump during one crossing of the Galactic disk is
(9) Then we calculate the tidal mass loss by clumps using a distribution of their orbits in the standard Navarro-Frank-White Galactic halo. Choosing a time interval t::..T much longer than a clump orbital period Tt, but much shorter than the age of the Galaxy to, i. e., Tt « t::..T « to, we define an averaged rate of mass loss by a selected clump under influence of tidal shocks in successive disk crossings:
セ@
(d:)d セ@ 1 (J:)d' t::..T L
(10)
The simplification in calculation of (10) follows from the fact that a velocity of orbit precession is constant. For this reason the points of successive odd crossings are separated by the same angles and the same is also true for successive even crossings. By the similar formalizm we calculate the diminishing of a clump mass due to a tidal heating by stars in the halo and bulge [9J. Combining together the rates of mass losses due to the tidal stripping of a clump by the disk and stars we obtain the evolution equation for a clump mass:
dM
dt =
(dM) dt
(dM)
d
+ dt
s'
(11)
233
3 kpc. / /' /' /'
/'
/8.5 kpc
/ 10 8 セ@
______セ@
________L -____セ@
____________セ@
______セ@
Figure 1: Numerically calculated modified mass function of clump remnants for galactocentric distances 3 and 8.5 kpc. The solid curve shows initial mass function.
We solve this equation numerically starting from the time of Galaxy formation at to - to up to the present moment to and calculate the probability P of the survival of clump remnant during the lifetime of the Galaxy. 4
Modified distribution function of clumps
We calculated (see details in [12]) the modified mass function for the smallscale clumps in Galaxy taking into account clump mass loss instead of clump destruction considered in [9]. One can see in the Fig. 1 that clump remnants exist below the Mmin. Deep in the bulge (very near to the Galactic center) the clump remnants are more numerous beca'use of intensive clump destructions in the dense stellar environment in comparison with the rarefied one in the halo. In [15] it was found that almost all small-scale clumps in Galaxy are destructed by tidal interactions with stars and transformed into "ministreams" of DM. The properties of these ministreams may be important for the direct detection of DM particles because DM particles in streams arrive anisotropic ally from several discrete directions. We demonstrate that the cores of clumps (or clump remnants) survive in general during the tidal destruction by stars in the Galaxy. Although their outer shells are stripped and produce the ministreams of DM, the central cores are protected by the adiabatic invariant and survived as the sources of annihilation signals.
234
5
Annihilation of dark matter in clumps
A local annihilation rate is proportional to the square of DM particle number density. A number density of DM particles in clump is much large than a corresponding number density of the diffuse (not clumped) component of DM. For this reason an annihilation signal from even a small fraction of DM clumps can dominate over an annihilation signal from the diffuse component of DM in the halo. The gamma-ray flux from annihilation of diffuse distribution of DM in the halo is proportional to rmax(()
IH =
J ーセHI@
(12)
dx,
o where PH - is the density profile of halo, integration over r goes along the line of sight, セHL@ r) = (r2 + イセ@ - 2rr8 cos ()1/2 is the distance to the Galactic - イセ@ sin 2 ()1/2 + r8 cos ( is a distance to the external center, rmax(() = Hrセ@ halo border, ( is an angle between the line of observation and the direction to the Galactic center, RH is a radius of the Galactic halo, r8 = 8.5 kpc is the distance between the Sun and Galactic center. The corresponding signal from annihilations of DM in clumps is proportional to the quantity [9] rmax (()
lei
=
s
J J セゥョエHmI@ dx
o
d:: ーphHセIL@
p)
(13)
Mmin
where p(M) is the mean density of clump, S セ@ 14.5 [9]. The observed amplification of the annihilation signal is defined as T/(() = (lcl - IH)/IH is shown in the Fig. 2 for the relative core's radius Rei R = 0.1. It tends to unity at ( -> 0 because of the divergent for in of the halo profile. This amplification of an annihilation signal is often called a 'boost factor'. A boost factor of the order of 10 is required for interpretation of the observed EGRET gamma-ray excess as a possible signature of DM neutralino annihilation [16]. The usual assumption in calculations of DM annihilation is a spherical symmetry of the Galactic halo. In this case an anisotropy of annihilation gammaradiation is only due to off-center position of the Sun in the Galaxy. Nevertheless, in [15] the anisotropy with respect to the Galactic disk was discussed. A tidal heating and final destruction of clumps by the gravitational field of the Galactic disk depends on the inclination angle of a clump orbit to the disk. In the Fig. 3 the annihilation signal [9] is shown for the Galactic disk plane and for the orthogonal vertical plane (passing through the Galactic center) as function of angle ( between the observation direction and the direction to the Galactic center. For comparison in the Fig. 3 is also shown the signal from
235
250 :r: 200
H
'-
:r: 150 +
H
rl
U
H
100 50 0 25
0
75
50
100
125
150
175
Sf degree Figure 2: The amplification of the annihilation signal (Ie! - IH)/IH as function of the angle between the line of observation and the direction to the Galactic center, where fluxes are given by (12) and (13).
9J)
H
25
50
75
S,
100
125
150
175
degree
Figure 3: The annihilation signal in the Galactic disk plane and in vertical plane.
236
the spherically symmetric Galactic halo without the DM clumps. The later signal is the same in the in the Galactic disk plane and in vertical plane and therefore can be principally extracted from the observations. The difference of the signals in two orthogonal planes at the same ( can be considered as an anisotropy measure. Defined as 8 = (12 - h)/h, it has a maximum value 8 セ@ 0.09 at ( セ@ 39°. This anisotropy provides a possibility to discriminate dark matter annihilation from the diffuse gamma-ray backgrounds of other origin. Acknowledgments
This work was supported in part by the Russian Foundation for Basic Research grants 06-02-16029 and 06-02-16342, the Russian Ministry of Science grants LSS 4407.2006.2 and LSS 5573.2006.2. References
[1] [2] [3] [4] [5] [6J [7] [8] [9J [10] [11] [12J [13] [14J [15] [16]
C.Schmid, D.J.Schwarz and P.Widerin, Phys. Rev. D 59,043517 (1999). D.J.Schwarz and S.Hofmann, Nucl. Phys. Proc. Suppl. 87, 93 (2000). H.S.Zhao , J.Taylor, J.Silk and D.Hooper, arXiv:astro-ph/0502049v4. A.M.Green, S.Hofmann and D.J.Schwarz, JCAP, 0508, 003 (2005). J.Diemand, M.Kuhlen and P.Madau, Astrophys. J. 649, 1 (2006). A.M.Green and S.P.Goodwin, Mon. Not. Roy. Astron. Soc. 375, 1111 (2007). E. Bertschinger, Phys. Rev. D 74, 063509 (2006). G.W. Angus and H.S.Zhao Mon. Not. Roy. Astron. Soc. 375, 1146 (2007). V.Berezinsky, V.Dokuchaev and Yu.Eroshenko, Phys.Rev. D 68, 103003 (2003); Phys.Rev. D 73, 063504 (2006); JCAP 07, 011 (2007). A.V.Gurevich and K.P.Zybin, Sov. Phys. - JETP 67, 1 (1988); Sov. Phys. - JETP 67, 1957 (1988); Sov. Phys. - Usp. 165, 723 (1995). J.Diemand, B.Moore and J.Stadel, Nature 433, 389 (2005). V.Berezinsky, V.Dokuchaev and Yu.Eroshenko, arXiv:0712.3499vl. J.P.Ostriker, L.Spitzer Jr. and R.A.Chevalier, Astrophys. J. Lett. 176, 51 (1972). O.Y.Gnedin and J.P.Ostriker, Astrophys.J. 513, 626 (1999). H.S.Zhao, J.Taylor, J.Silk and D.Hooper, arXiv:astro-ph/0508215v4. W. de Boer, C.Sander, V.Zhukov, A.V.Gladyshev and D.I.Kazakov, Astron. Astrophys. 444, 51 (2005).
CURRENT OBSERVATIONAL CONSTRAINTS ON INFLATIONARY MODELS E.Mikheeva a Astra Space Centre, P.N.Lebedev Physics Institute, 117997 Moscow, Russia Abstract. We review current observational constraints on inflationary models and show that A-inflation is observationally favored.
1
Introduction
Proposed more than two decades ago inflation successfully and elegantly solved a majority of existed cosmological problems (see e.g. [1]). Now we are on the way to selecting the inflationary model that was realized in the beginning of the Universe. On this way there is a lot of troubles. The first of them is a great gap between long lasting inflation (more than 60 e-folds) and rather short interval of observable cosmological scales (from 10 Mpc to the present horizon, about 6 e-folds). So, only a short interval of inflaton values can be directly tested and a narrow part of the potential can be reconstructed. Nowadays there is a single inflationary paradigm, but a lot of inflationary models. A long list of these models includes more than two hundred items. In this paper we concentrate on available observational constraints for inflationary models with a single scalar field, which allow us to simplify the problem. 2
Model and observable quantities
If the potential of inflaton is fixed then spectra of cosmological perturbations generated during inflation can be derived. In the case of scalar field the seeds for vector mode of perturbations are absent and we deal only with scalar and tensor modes of cosmological perturbations. The former is related to density perturbations, the latter is gravitational waves. Both spectra are functions of wave number k. Testing inflation in a straighforward way means constraining predicted spectra by different sets of observational data. Observationally, it is more convenient to operate with simplified presentations of the power spectra as follows:
(1) where S(k) is the spectrum of scalar perturbations, T(k) is the spectrum of tensor perturbations, As and AT are amplitudes of the spectra, ns and nT are the spectra slopes of scalar and tensor modes, respectively. A further presentation of spectra in parameter space is acceptable for scalar mode: &ns a=&lnk' ae-mail: [email protected]
237
(2)
238 where a is a running index. The value of a is a measure of deviation of the scalar spectral index from the power law. Another observationally convenient quantity is a relative amplitude of gravitational waves, TIS. Initially it was introduced as a ratio of contributions of gravitational waves and density perturbations into large scale anisotropy of cosmic microwave background (a quadrupole or 10 angular degree anisotropy). Here TIS is a ratio of the tensor to scalar power spectrum for k c:::: 1O- 3 Mpc- 1 . So, from model functions S(k) and T(k) we pass to observable quantities ns, TIS, and a. 3
Classification of inflationary models
Inflationary models with a single scalar field can be classifying as follows ( [2]): 1) inflation on small field, with example potential V(ip) where Vo, ipo and p are positive constants;
= Va [1 - (iplipo)PJ,
2) inflation on large field, with power-law potentials as an example V(ip) '"
ipP 3) A-inflation with example potential V(ip) are positive constants.
= Vo + AipP 14, where Vo and A
This simple classification is rather convenient to design inflationary model predictions on the plot TIS - ns. 4
Current observational constraints for inflationary models
Observational cosmology deals with a long list of cosmological parameters (cosmological constant value D A , amount of cold dark matter Dcdm), Hubble constant Ho and many others). Reconstruction of parameters related to the inflationary stage of the expansion may be considered as a reduced task, but it does not simplify the problem. So, uncertainties of constraints for all these cosmological parameters will be imprinted on the values of ns, TIS and a, and their error bars, as well. Nevertheless, in the first decade of the third millennium we have a powerful tool to determine inflationary cosmological parameters. It is a joint statistical analysis of different kinds of observational data, including data on Cosmic Microwave Background anisotropy (see [5]). Of cause, CMB data alone have some degeneracies, which can be removed by taking into account available data on galaxy distributions. This approach allows one to find probability distribution contours for three classes of inflation on the plain TIS - ns. It appears that current observational data rather strongly constrain ns, which is forbidden to strongly deviate from the Harrison-Zel'dovich value (ns =
observational constraints on intlatilonlary large field inflations and between large field inflation (on the corresponds to constraints on A-inflation from to a confidence level by the line line with a confidence level The h"f'kO'r""mri case of nonzero running index.
way to detect B-mode of the CMB constraints on UJlVl\JI4"''''''''
rarneters is not the
240
of problems in determining cosmological parameters caused by inflation. Another source is a priori hypotheses used during reconstruction of the parameters. Assuming a = 0 which is reasonable for some kinds of inflationary models 10- 3 ), decreases a possible value (for example, in massive field inflation lal of T / S twice. Rejection of this assumption dramatically leads from the set (ns = 0.98 ± 0.03, T / S < 0.17, see Table 7 in [5]) to the set (ns = 1.16 ± 0.1, T / S < 0.3, ibid). Statistically the difference is negligible, theoretically it is huge. In particular, it means that a real error of determination of ns is about 0.1, therefore "blue" spectra of density perturbations do not contradict available observational data. r-.J
5
Conclusions
Our conclusions are the following: 1. Massive field inflation satisfies available observational data. Chaotic inflation with potential slope p セ@ 4 (see) is rejected by observations. 2. If further observations indicate ns > 1 then some variant of A-inflation was realized in the early Universe. If observations fix ns < 1 then there was inflation on massive scalar field, or small field inflation, or something else depending on the values of ns and T / S. 3. Inflationary model will be determined in the nearest future. Acknowledgment
This work was supported by Russian Foundation for Basic Research (grant number 07-02-00886). References
[1] A.Linde, "Particle Physics and inflationary cosmology", (Harwood Academic Publishers, Chur, Switzerland), 1990. [2] W.H.Kinney, A.Melchiorri, A.Riotto, Phys. Rev. D 63, 023505 (2001). [3] A.Linde, Phys. Rev. D 49, 748 (1994). [4] V.N.Lukash, E.V.Mikheeva, Int. J. Mod. Phys. A 15, 3783 (2000). [5] D.N.Spergel, ApJ Supp. 170, 377 (2007). [6] E.V.Mikheeva, V.N.Lukash, Astron. Rep. 48, 2 (2004); in Russian Astron. Zh. 81, 4 (2004).
PHASE TRANSITIONS IN DENSE QUARK MATTER IN A CONSTANT CURVATURE GRAVITATIONAL FIELD
2
D. Ebert la , V. Ch. Zhukovskyl>, and A. V. Tyukov 2 1 Institut fur Physik, Humboldt- Universitiit zu Berlin, 12489 Berlin, Germany Faculty of Physics, Department of Theoretical Physics, Moscow State University, 119899, Moscow, Russia Abstract We consider the phase transitions in dense matter with quark and diquark condensates in the static Einstein universe at finite temperature and chemical potential. The nonperturbative expression for the thermodynamic potential was obtained. The phase portraits of the system were constructed.
1
Introduction
It was proposed more than twenty years ago [2,3] that at high baryon densities a colored diquark condensate < qq > might appear. In analogy with ordinary superconductivity, this effect was called color superconductivity (CSC). The possibility for the existence of the CSC phase in the region of moderate densities was recently proved (see, e.g., the papers [4-6]). Since quark Cooper pairing occurs in the color anti-triplet channel, a nonzero value of < qq > means that, apart from the electromagnetic U(I) symmetry, the color SUc (3) symmetry should be spontaneously broken inside the CSC phase as well. The similar effect of chiral symmetry breaking in curved spacetime has been recently studied [7,8], which may be useful for the investigation of compact stars, where the gravitational field is strong and its effect cannot be neglected.
2
The extended NJL model in curved space-time
We will use the extended Nambu - Jona-Lasinio (NJL) model [1] with upand down-quarks and color group SU(3)c. This model may be considered as the low energy limit of QCD. The linearized Lagrangian with collective boson fields (J', if and .6. can be written in the form: i'
'-
t,
t,
-[.1-'" of. 0, the chiral symmetry is broken dynamically, and if < /::,. b > of. 0, the color symmetry is broken. The effective action for boson fields Seff can be expressed through the integral over quark fields, according to
In the mean field approximation, the fields a, if, /::,.b, /::,.*b can be replaced by their groundstate averages: < a >, < if >, < /::,. b > and < /::,. *b >, respectively. Let us choose the following ground state of our model: < /::,.1 > = < /::,. 2 > = < if > = 0, and denote < a >, < /::,.3 > of. 0, by letters a, /::,.. Evidently, this choice breaks the color symmetry down to the residual group SUc (2). Let us find the effective potential of the model with the global minimum point that will determine the quantities a and /::,.. By definition Seff = - Veff dD xFg, where
J
-
Veff
3
= MセG@
Sq
V
=
J
d D xF9.
(3)
Static Einstein universe
We will use the static D-dimensional Einstein universe as the simple example of curved spacetime. The line element is
(4) where a is the radius of the universe, related to the scalar curvature by the relation R = (D - l)(D - 2)a- 2 . The effective potential at finite temperature or thermodynamic potential may be obtained in the following form (for more details see [9]) ,,2 O(a, /::,.) = 3 ( 2G, N
00
2: dl {El + Tin (1 + e-t3CEI-lLl) + Tin (1 + e-t3CEI+lLl)}
-::,; (Nc - 2)
-::,; E N
1Ll.12) + e;-
00
+2TIn
dl
1=0 {
J(EI - J1.)2
+ 41/::,.1 2 + J(EI + J1.)2 + 41/::,.1 2 +
(1 + e- y'CE -lLl 2+41Ll.1 2) + 2T In (1 + e- t3 y'CE t3
1
where V is the volume of the universe V(a) El
=
V1( D-1)2 - 1+ - +a a 2 ' 2
2
1 +1L)2+41Ll.1
= 27l'D/2a D- 1 /r( セIL@ 1= 0, 1,2 ... ,
2 ) },
(5)
(6)
243
and d _
2[(D+l)/2 j qD
+l -
l!r(D _ 1)
I -
1) ,
(7)
where [xl is the integer part of x. 4
Phase transitions
In what follows, we shall fix the constant G 2 , similarly to what has been done in the flat case [5,10], by using the relation G 2 = セgャN@ For numerical estimates, let us choose the constant G 1 = 10 such that the chiral and/or color symmetries were completely broken. Moreover, let us now limit ourselves to the investigation of the case D = 4 only. In Fig. 1, the J1, - R-phase portrait of the system at zero temperature is depicted.
6 4
2 2 ______ L-_____________ R セ@
o
10
20
30
40
Figure 1: The phase portrait at T=O. Dashed (solid) lines denote first (second) order phase transitions. The bold point denotes a tricritical point.
For points in the symmetric phase 1, the global minimum of the thermodynamic potential is at (j = 0, t. = 0 (chiral and color symmetries are unbroken). In the region of phase 2, only chiral symmetry is broken and (j =1= 0, t. = O. The points in phase 3 correspond to the formation of the diquark condensate (color superconductivity) and the minimum takes place at (j = 0, t. =1= O. Moreover, the oscillation effect clearly visible in the phase curves of Fig. 1 should be mentioned. This may be explained by the discreteness of the fermion energy levels (6) in the compact space. This effect may be compared to the similar effect in the magnetic field H, where fermion levels are also discrete (the Landau levels). In Fig. 2, J1, - R- and T - J1,- phase portraits are depicted. It is clear from Fig.2 that with growing temperature both the chiral and color symmetries are restored. The similarity of plots in R - J1, and J1, - T axes leads one to the conclusion that the parameters of curvature R and temperature T play similar roles in restoring the symmetries of the system.
244
3.5
Jl
5
Jl
3
2.5 3
2
3
1.5 2 2
0.5 lMセGr@
4
6
8
10
12
14
16
'--------------L--T 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Figure 2: The phase portraits at T=O.35 (left picture) and at R=3 (right picture).
We have considered the phase transitions in the static Einstein universe at finite temperature and chemical potentia!. In spite of the model character of the problem, we hope that the results of this paper may stimulate further investigations that are closer to realistic cosmological or astrophysical situations. Acknow ledgments
One of the authors (A.V.T.) is grateful to Prof. M. Mueller-Preussker for his attention and support of this work. This work was also supported by DAAD. References
[1] Y. Nambu and G. Jona-Lasinio, Phys. Rev. 122, 345 (1961); 124, 246 (1961); ibid. 124, 246 (1961); V. G. Yaks and A. I. Larkin, ZhETF 40, 282 (1961). [2] B.C. Barrois, Nuc!. Phys. B 129, 390 (1977). [3] D. Bailin and A. Love, Phys. Rept. 107, 325 (1984). [4] M. Alford, K. Rajagopal and F. Wilczek, Nuc!. Phys. B 537, 443 (1999); K. Langfeld and M. Rho, Nuc!. Phys. A 660, 475 (1999). [5] J. Berges and K. Rajagopal, Nuc!. Phys. B 538, 215 (1999). [6] T.M. Schwarz, S.P. Klevansky and G. Papp, Phys. Rev. C 60, 055205 (1999). [7] T. Inagaki, S.D. Odintsov and T. Muta, Prog. Theor. Phys. Supp!. 127, 93 (1997), hep-th!9711084 (see also further references in this review paper). [8] X. Huang, X. Hao, and P. Zhuang, hep-ph!0602186. [9] D.Ebert, A.V.Tyukov, and V.Ch. Zhukovsky, Phys. Rev. D76, 064029 (2007). [10] D. Ebert, V.V. Khudyakov, V.Ch. Zhukovsky, and K.G. Klimenko, Phys. Rev. D 65, 054024 (2002); D. Ebert, K.G. Klimenko, H. Toki, and V.Ch. Zhukovsky, Prog. Theor. Phys. 106,835 (2001).
CONSTRUCTION OF EXACT SOLUTIONS IN TWO-FIELDS MODELS Sergey Yu. Vernov a Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow, Russia Abstract.Dark energy model in the Friedmann Universe with a phantom scalar field, an usual scalar field and the polynomial potential has been considered. We demonstrate that the superpotential method is very effective to seek new solutions and to construct a two-parameter set of exact solutions to the Friedmann equations. We show that the standard formulation of superpotential method can be generalized.
1
Introduction
One of the most important recent results of the observational cosmology is the conclusion that the Universe expansion is speeding up rather than slowing down. The combined analysis of the type Ia supernovae, galaxy clusters measurements and WMAP (Wilkinson Microwave Anisotropy Probe) data gives strong evidence for the accelerated cosmic expansion [1-3]. To specify a component of a cosmic fluid one usually uses a phenomenological relation between the pressure p and the energy density {} corresponding to each component of fluid p = W{}, where W is called as the state parameter. The experimental data suggests that the present day Universe is dominated by a smoothly distributed slowly varying cosmic fluid with negative pressure, the so-called dark energy. Contemporary experiments [1-3] give strong support that the Universe is approximately spatially flat and the dark energy state parameter w DE is currently close to -1: w DE = -1 ± 0.2. The state parameter wDE == -1 corresponds to the cosmological constant. As it has been shown in [4] for a large region in parameter space an evolving state parameter wDE is favoured over w DE == -1. The standard way to obtain an evolving state parameter WDE is to include scalar fields into a cosmological model. Two-fields cosmological models, describing the crossing of the cosmological constant barrier wDE == -1, are known as quintom models and include one phantom scalar field and one usual scalar field. Nowadays the string field theory (8FT) has found cosmological applications related to the acceleration of the Universe. In phenomenological phantom models, describing the case WDE < -1, all standard energy conditions are violated and there are problems with stability (see [5] and references therein). Possible way to evade the instability problem for models with WDE < -1 is to yield a phantom model as an effective one, which arises from more fundamental theory with a normal sign of a kinetic term. In this paper we consider a 8FT inspired gravitational models with two scalar fields and a polynomial potentials. We propose new formulation of superpotential method, which is more suitable to construct models with a two-parameter set of exact solutions. ae-mail: [email protected]
245
246
2
String Field Theory Inspired Two-Fields Model
We consider a model of Einstein gravity interacting with a phantom scalar field ¢ and a standard scalar field セ@ in the spatially flat Friedmann Universe. We assume that a phantom scalar field represents the open string tachyon, whereas the usual scalar field corresponds to the closed string tachyon [6-8]. Since the origin of the scalar fields is connected with the string field theory the action contains the typical string mass Ms and a dimensionless open string coupling constant go:
s=
JdxA (::1;R + Zセ@ 4
HセァiGv。ャᄁカ@
-
。ャGセカI@
-
vHᄁLセI@
(1)
where Mp is the Planck mass. The Friedmann metric gl'v is a spatially flat:
(2) where a(t) is a scale factor. The coordinates (t, Xi) and fields ¢ and dimensionless. If the scalar fields ¢ and セ@ depend only on time, then
H2 =
_1_ ( _
Sュセ@
if =
¢ + 3H 4> =
セ@
Rセ@
セ@ 12 2'1-'
セ@ c2
+ 2'" +
v) ,
セ@
+ 3He = -
are
(3)
(4)2 - e) ,
== V,;,
セ@
セ@
(4)
== - V(
(5)
For short hereafter we use the dimensionless parameter mp: ュセ@ = ァ[mセェZN@ Dot denotes the time derivative. The Hubble parameter H == a(t)ja(t). Note that only three of four differential equations (3)-(5) are independent.
3
The Method of Superpotential
The gravitational models with one or a few scalar fields play an important role in cosmology and models with extra dimensions. One of the main problems in the investigation of such models is to construct exact solutions for the equations of motion. System (3)-(5) with a polynomial potential vHᄁLセI@ is not integrable. The superpotential method has been proposed for construction of a potential, which corresponds to the particular solutions known in the explicit form [9]. The main idea ofthis method is to consider H(t) as a function (superpotential) of scalar fields: H(t) = wHᄁエILセN@ (6) If we find such superpotential W HᄁLセI@
that the relations
(7)
247
(8) are satisfied, then the corresponding cp, セ@ and H are a solution of (3)-(5). The superpotential method separates system (3)-(5) into two parts: system and equation (7), which is as a rule integrable for the given polynomial W H」ーLセI@ (8), which is not integrable if vH」ーLセI@ is a polynomial, but has exact special solutions. The use of superpotential method does not include the solving of eq. (8). The potential vH」ーLセI@ is constructed by means of the given wH」ーLセIN@ Relations (7) and (8) are sufficient, but maybe not necessary conditions to satisfy (3)-(5). To generalize them we assume that functions cp(t) and セHエI@ are given by the following system of equations: fH」ーLセI@
¢=
(9)
where fH」ーLセI@ and gH」ーLセI@ are some differentiable functions. We consider these functions as given ones and transform system (3)-(5) into equations in W(cp, セIZ@
W2 = _1_ ( _
Sュセ@
W' F ¢
セ@ F2 2
+ W'G = E
セgR@ +2
+
v) ,
(10)
_1_ (F2 _ G2 ) 2m2p '
(11)
F/pF + fセg@ + 3WF = V,;, G;PF + GeG + 3WG = -
(12)
vt
We differentiate equation (10) in
W ( W/p -
Rセ@
(13)
cp and use (12) to exclude VJ,: F)
Vセ@
=
(G ¢
+ FE) .
(14)
Similar manipulations give also
WHwセ@ For any gH」ーLセI@
and fH」ーLセI@
+ Rセ@
G) = -
such that G¢
2m;W';' = F,
Rュ[wセ@
=
Vセ@
(G¢
+ FE) .
-FE we find
= -G.
wH」ーLセI@
(15) using relations (16)
These relations are equivalent to (7). In this case the equality G¢ = -FE is ァセ@ = ァセN@ So, we have shown that the relations (7) are necessary conditions if and only if the equality G¢ = -FE is satisfied. In other case one should solve nonlinear system (14)-(15) to find the corresponding superpotential wH」ーLセIN@ Note that in our formulation we do not use the explicit form of exact solutions to find potential. Note also that for one and the same one-parameter set of exact
248
solutions we can find different form of functions F and G and, therefore, the different form of potential V. We can conclude that the proposed formulation of the superpotential method is effective to seek potential V (¢, セIL@ which satisfies some conditions and corresponds to a two-parameter set of exact solutions. For example, if F and G are linear functions (A, Band C are constants): (17) then we obtain the fourth degree polynomial potential
V =
A2
- B2 ᄁRKbHacIセ@
B2
2
-
C2
2
3 ( e + - -2 aᄁRKbセMc・@
)2
16mp
. (18)
and two-parameter set of exact solutions for the Friedmann equations. For example, at C = 2B + A we obtain (Cl and C 2 are arbitrary constants) and
セ@
=
(C + C;; + l
C2t)
e(A+B)t.
(19)
More nontrivial example with the sixth degree polynomial potential and a twoparameter set of kink-like (¢) and ャオューセゥォ・@ HセI@ solutions is presented in [8]. Acknowledgments
Author is grateful to LYa. Aref'eva for useful discussions. This research is supported in part by RFBR grant 05-01-00758 and by grant NSh-8122.2006.2. References
[1] A. Riess et al. [Supernova Search Team Collaboration], Astron. J. 116, 1009-1038 (1998); astro-ph/9805201. [2] D.N. Spergel et al. [WMAP Collaboration]' Astrophys. J. Suppl. SeT. 170 377-408 (2007); astro-ph/0603449. [3] Tegmark et al. [SDSS Collaboration], Phys. Rev. D69 103501 (2004); astro-ph/0310723. [4] U. Alam, V. Sahni, T.D. Saina, A.A. Starobinsky, Mon. Not. Roy. Astron. Soc. 354, 275 (2004); astro-ph/0311364 [5] LYa. Aref'eva, LV. Volovich, 2006, hep-th/0612098. [6] LYa. Aref'eva, AlP Conf. Proc. 826301-311 (2006); astro-ph/0410443. [7] LYa. Aref'eva, A.S. Koshelev, S.Yu. Vernov, Phys. Rev. D72, 064017 (2005); astro-ph/0507067. [8] S.Yu. Vernov, 2006, astro-ph/0612487. [9] O. DeWolfe, D.Z. Freedman, S.S. Gubser, A. Karch, Phys. Rev. D62, 046008 (2000); hep-th/9909134.
QUANTUM SYSTEMS BOUND BY GRAVITY Michael L. Fil'chenkov a , Sergey V. Kopylov b , Yuri P. Laptev C Institute of Gravitation and Cosmology, Peoples' Friendship University of Russia, Moscow Department of Physics, Moscow State Open University Department of Physics, Bauman Moscow State Technical University Abstract. Quantum systems contain charged particles around mini-holes called graviatoms. Electromagnetic and gravitational radiations for the graviatoms are calculated. Graviatoms with neutrino can form quantum macro-systems.
Introduction
1
As known, there exist bound quantum systems due to electromagnetic and strong interactions, e.g. atoms, molecules and atomic nuclei. If one component of the gravitationally bound system is assumed to be massive and the other is an elementary particle, then a quantum system can be formed, e.g. mini-holes in the early Universe [1-3]. Such systems are called graviatoms [4]. Another example of the quantum systems bound by gravity is macro-bodies capturing neutrinos having de Broglie's wave length of macroscopic value.
2
Theoretical solution to the graviatom problem
Schrodinger's equation for the graviatom [2]
セ@
[r2 (dR pl )] r2 dr dr
2 2 _l(l r2+ 1) R P1+ 2m (E _ mc rQr g + mc r g ) 1i 2 4r2 2r
R 1 = 0 (1) P
describes a radial motion of a particle with the mass m in the mini-hole potential, where rg = 2GM/c 2 and M are the mini-hole gravitational radius and mass respectively. The energy spectrum is of hydrogen-like form
E 3
G2 M 2 m 3 21i 2 n 2
= ----,:--
(2)
Graviatom existence conditions
A graviatom can exist if the following conditions are fulfilled [4]: 1) the geometrical condition L > r 9 + R, where L is the characteristic size of the graviatom, R is that of a charged particle; 2) the stability condition: (a) Tgr < TH, where Tgr is the graviatom lifetime, TH is the mini-hole lifetime, (b) Tgr < T p , where Tp is the particle lifetime (for unstable particles); 3) the indestructibility condition (due to tidal forces and Hawking's effect) Ed < Eb, where Ed is the destructive energy, Eb is the binding energy.
249
250
____ lMLセ⦅
0.5
1.0
セ@
__
2.5
2.0
1.5
セ@
3.0
_ _ _ _ _ m·l0· 3.5
21
,g
4.0
Figure 1: The dependence of mini-hole masses on the charged particle masses satisfying the graviatom existence conditions. The light curves indicate the range of values related to the geometrical condition (the upper curve) and to Hawking's effect ionization one (the lower curve). The heavy curve is related to the particle stability condition (Tp = 1O- 22 s).
The charged particles able to be constituents of the graviatom are: the electron, muon, tau lepton, wino, pion and kaon. The conditions of existence the graviatoms reduce to the relation between the masses of the mini-hole and particle, with their product being approximately constant equal to the Planck mass squared. 4
Graviatom radiation
The intensity of the electric dipole radiation of a particle with mass m and charge e in the gravitational field of a mini-hole reads [4] 2
d
I fi
=
2fie w7f lif me3
'
(3)
where wif = (Ei - E f )/fi is the frequency of the transition i --> I and lif is the oscillator strength [5]. The electric quadrupole radiation intensity for the transition 3d --> Is is q
113
=
6fie 2 wg1 3 me
hd--+1s'
(4)
The gravitational radiation intensity for the graviatom performing the transition 3d --> Is reads 9 _ 6fiGMwg 1 113 3 hd--+1s' (5) e The mini-hole creates particles near its horizon due to Hawking's effect, its power [7].
251 Table 1: Parameters for graviatoms with the electron and wino [6].
electron 0.511
mc"'!', MeV
8
00
M, g L, cm
3.5.10 17 6.10 11 0.08 2. lOw
T,
hW12,
Id(2p
MeV 18), erg.
--t
8 ·1
wino 8 . lOt> 5. 10 -10 2.2. lOll 4.10 17 1.2. lOt> 4 .1O:.!",!.
The mini-holes being constituents of the graviatoms are formed due to Jeans' gravitational instability at the times about セ@ c = 10- 27 -;.-10- 21 8 from the initial singularity. The mini-hole masses for the graviatoms involving electrons, muons and pions exceed the value of 4.38 . 1014g, which means that it is possible for such graviatoms to have existed up to now [7]. The quantity gセュ@ = 0.608 -;.- 0.707 is a gravitational equivalent of the fine structure constant. The gravitational radiation intensities two orders exceed the electromagnetic ones. The graviatom dipole radiation energies and intensities have proved to be comparable with those for Hawking's effect of the mini-holes being constituents of the graviatoms. 5
Systems with neutrinos
De Broglie's wavelength for the neutrino with mass mv is
1) Graviatom The existence conditions: 。セ@ = li.dB > 3rg, Tgr < energy: mvc2 rv 1 eV. Characteristic frequency:
TH.
Electron neutrino rest
Gravitational radiation: Igr =
Q9M9 m ll
c5 h lO
v
Mini-hole masses: 10 18 g < M < 10 23 g. For example, if M < 10 23 g, then ィキセ@ < 0.2 eV,Igr size is about 10 1 -;.- 106 cm.
(8)
< 0.2 erg·8- 1 . System
252 2) Macroscopic system (comet nuclei, meteorites, small asteroids) Macro-bodies capture neutrinos onto both Bohr's hydrogen-like levels (outside the body) and Thomson's oscillatory ones (inside the body). Macro-body masses: 10 14 g < M < 10 19 g. Bohr's radius is about:
1 -;- 10 5 cm. The oscillation frequency w intensity
=
J!7fpG, the gravitational radiation (9)
where p is the macro-body density. Let consider the average density of a macro-body p equal to 4 g·cm- l . Then, we obtain the following parameters: fiw = 9.10- 19 eV, 1mb = 10- 104 erg· 8- 1 . It is of interest to note that the rotation curves of galaxies give an aI-most constant velocity v on their periphery, which for v 2 "" G M / R leads to the dependence of dark matter mass Mdm "" R, similar to the dependence of the mass of neutrinos on Bohr's radius L, since L = 。セョRL@ and the total mass of all neutrinos on the nth level is equal to Mn = 2n 2 m v . Hence, we obtain Mn "" L. 6
Conclusion
The graviatom can contain only leptons and mesons. The observable stellar magnitude for graviatom electromagnetic radiation exceeds 23m. Stable graviatoms with baryon constituents are impossible. The internal structure of the baryons, consisting of quarks and gluons, should be taken into account. There occurs a so-called quantum accretion of baryons onto a mini-hole. The whole problem is solvable within the frame-work of quantum chromo dynamics and quantum electrohydrodynamics. Neutrinos can form quantum macro-systems. The description of gravitationally bound macro-systems with neutrinos may be helpful for solving the dark matter problem in the Universe. References
[1] [2] [3] [4]
A.B. Gaina, PhD Thesis, Moscow State University, Moscow, 1980. M.L. Fil'chenkov, Astron. Nachr. 311, 223 (1990). M.L. Fil'chenkov, 1zvestiya Vuzov, Fizika No.7, 75 (1998). Yu.P. Laptev, M.L. Fil'chenkov, Electromagnetic and Gravitational Radiation of Graviatoms/ / Astronomical and Astrophysical Transactions. 2006. v. 25, No.1, p. 33 - 42 [5] H.A. Bethe and E.E. Salpeter, "Quantum Mechanics of One- and TwoElectron Atoms", Springer-Verlag, Berlin, 1957. [6] M. Sher, hep-th/9504257. [7] V.P. Frolov, in "Einstein Col." 1975-1976, Nauka, Moscow, 1978, p. 82-151.
CP Violation and Rare Decays
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SOME PUZZLES OF RARE B-DECAYS A.B. Kaidalov a
Institute of Theoretical and Experimental Physics, 117259 Moscow, Russia Abstract. It is emphasized that a study of rare B-decays provides an important information not only on CKM-matrix, but also on QCD dynamics. It is shown that some puzzles in B-decays can be explained by final state interaction (FSI). The model for FSI, based on Regge phenomenology of high-energy hadronic interactions is proposed. This models explains the pattern of phases in matrix elements of B ---> 'Tr'Tr and B ---> pp decays. These phases play an important role for CPviolation in B-decays. It is emphasized that the large distance FSI can explain the structure of polarizations of vector mesons in B-decays and very large branching ratio of of the B-decay to SeAc.
1
Introduction
This short review of some unusual properties of matrix elements in hadronic B-decays is based on papers with M.l. Vysotsky [1,2J. Detailed information on B-decays, obtained in experiments at B-factories [3J, provide a testing ground for theoretical models. Investigation of rare B-decays and CP violation in these decays provides not only an information on CKM matrix, but also on QCD dynamics both at small and large distances. One of the most interesting and still not solved problems in B-decays is the role of FSI. In this paper I shall demonstrate, that FSI play an important role ill hadronic B-decays and allow one to explain some puzzles observed in rare B-decays. In particular it will be shown that phases due to strong interactions are substantial in some hadronic B-decays. These phases are important for understanding the pattern of CP-violation in rare B-decays. The model for calculation of FSI will be formulated and compared to the data on B ----> 1r1r and B ----> pp decays. The model is based on regge-picture for high-energy binary amplitudes and allows also to explain a pattern of helicity non-conservation in some B-decays to vector mesons. Large distance interactions provide a simple explanation of anomalously large branching ratio of the B-decay to 3cAc. 2
B
----> 1r1r /
B
---->
pp puzzle
The probabilities of three B ----> 1r1r and three B ----> pp decays are measured now with a good accuracy. There is a large difference between ratios of the charged averaged Bd decay probabilities to the charged and neutral mesons.
ae-mail: [email protected]
255
256 It was demonstrated in refs. [1,2J that this difference is related to the difference of phases due to strong interactions for matrix elements of B ---; 1T1T and B ---; pp-decays. The matrix elements of these decays can be expressed in terms of amplitudes with isospin (I) zero and two with phases 6o and 62. To take into account differences in CKM phases for tree and penguin contributions we separate the amplitude with 1=0 into the corresponding parts A o and P. The contributions of P can be determined, using SU(3)-symmetry from decays Bu ---; KO* p+ and Bu ---; K01T+ [4] and turn out to be rather small compared to tree contributions. Note, however, that P determines magnitudes of direct CPV in hadronic decays. If we neglect the penguin contribution, then the difference of phases is expressed in terms of the branching ratios as follows
cos(oo -
on = -J3
B+_ - 2B oo
4 Jf!B+oJB+-
+ セ@
I!.L B+o
T+,
+ Boo - セヲAbKッ@
(2)
Using experimental information on branching ratios of B ---; 1T1T-decays [3J we obtain 160 - UセQ@ = 48°. Penguin contributions to Bik do not interfere with tree ones because CKM angle ex = 1T - (3 - 'Y is almost equal to 1T /2. With account of P-term we get:
(3) This value agrees with the result of analysis of ref. [5J:
6o - 62 = 40° ± 7° ,
(4)
Thus the difference of phases of matrix elements with 1=0 and 1=2 is not small in sharp contrast with factorization approximation often used for estimates of heavy mesons decays. For B ---> pp-decays we obtain in analogous way: (5)
This phase difference is smaller than for pions and is consistent with zero. The fact that phases due to FSI are in general not small for heavy quark decays is confirmed by other D and B-decays. The data on D ---> 1T+1T-, D ---> 1T01TO and D± ---> 1T±1TO branching ratios lead to [6J:
(6) The last example is B ---; D1T decays. D1T pair produced in B-decays can have I = 1/2 or 3/2. From the measurement of the probabilities of B- ---> D01T-, BO ---> D-1T+ and BO ---; D01To decays in paper [7J the FS1 phase difference of these two amplitudes was determined: (7)
257
Thus experimental data indicate that the phases due to FSI are not small for heavy mesons decays.
3
Calculation of the FSI phases of B plitudes
--+
7r7r and B
--+
pp decay am-
Let me remind that for K --+ 7r7r decays there are no inelastic channels, MigdalWatson (MW) theorem is applicable and strong interaction phases of S-matrix elements of K --+ (27r) I decays are equal the phases of the corresponding 7r7r --+ 7r7r scattering amplitudes at E = m K. For B-mesons there are many opened inelastic channels and MW theorem is not directly applicable. Serious arguments that strong phases should disappear in the MQ --+ 00 limit were given by B.J. Bjorken [8J. He emphasized the fact that characteristic configurations of the produced in the decay light quarks have small size"" l/MQ and FSI interaction cross sections should decrease as 1/ mセN@ Similar arguments were applied in the analysis of heavy quark decays in the QeD perturbation theory [9J. These arguments can be applied to the total hadronic decay rates. For individual decay channels (like B --+ 7r7r), which are suppressed in the limit MQ --+ 00 the situation is more delicate. However even in these situations the arguments of Bjorken that due to large formation times the final particles are formed and can interact only at large distances from the point of the decay seem relevant. On the other hand a formal analysis of different classes of Feynman diagrams, including soft rescatterings [10,11]. show that the diagrams with pomeron exchange in the FSI-amplitudes do not decrease as MQ increases. Same conclusions follow from applications of generalizations of MW-theorem [12,13J. In the process of analysis of FSI in heavy mesons decays it is important to understand a structure of the intermediate multi particle states. It was shown in ref. [2] that the bulk of multiparticle states produced in heavy mesons decays has a small probability to transform into two-meson final state and only quasi two-particle intermediate states XY with masses M.k(Y) < MBA QCD « mセ@ can effectively transform into the final two-meson state. In refs. [1, 2J in calculation of FSI effects for B --+ 7r7r and B --+ pp decays we considered only two particle intermediate states with positive G-parity to which B-mesons have relatively large decay probabilities. Alongside with 7r7r and pp there is only one such state: 7ral. I shall use Feynman diagrams approach to calculate FSI phases from the triangle diagram with the low mass intermediate states X and Y . Integrating over loop momenta d 4 k one can transform the integral over ko and k z into the integral over the invariant masses of intermediate particles X and Y
J
dkodk z =
Rセ@
J
dsxdsy
(8)
258 and deform integration contours in such a way that only low mass intermediate states contributions are taken into account while the contribution of heavy states being small is neglected. In this way we get:
I M7r7r
=
M(O)I(" XY U7r XU7r Y
+ 2'TJ=O) XY->7r'lf
,
(9)
where Mflf are the decay matrix elements without FSI interactions and Tiyo....7r7r is the J = 0 partial wave amplitude of the process XY -+ 'lor (TJ = (SJ - 1)/(2i)) which originates from the integral over d2 kJ... For real T (9) coincides with the application of the unitarity condition for the calculation of the imaginary part of M while for the imaginary T the corrections to the real part of M are generated. This approach is analogous to the FSI calculations performed in paper [14]. However in [14] 2 -+ 2 scattering amplitudes were considered to be due to elementary particle exchanges in the t-channel. For vector particles exchanges s-channel partial wave amplitudes behave as sJ-1 cv sO and thus do not decrease with energy (decaying meson mass). However it is well known that the correct behavior is given by Regge theory: s"'i(0)-1. For p-exchange Cfp(O) r::::J 1/2 and the amplitude decrease with energy as 1/.fS. This effect is very spectacular for B -+ DD -+ 'WIT chain with D*(D2) exchange in t-channel: CfD*(O) r::::J -1 and reggeized D* meson exchange is damped as S-2 r::::J 10- 3 in comparison with elementary D* exchange (see for example [13]). For 71'-exchange, which gives a dominant contribution to pp -+ 71'71' transition (see below), in the small t region the pion is close to mass shell and its reggeization is not important. Note that the pomeron contribution does not decrease for MQ -+ 00, however I which we are interested it does not contribute to the difference of phases IJg Mjセ@ in. So this phase difference is determined by the secondary exchanges p, 71' and it decreases at least as 1/MQ for large MQ in accord with Bjorken arguments. For phases J and jセ@ I separately the pomeron contribution does not cancel in general. If Bjorken arguments are valid for these quantities it can happen only under exact cancellation of different diffractively produced intermediate states and it does not happen in the model of refs. [1,2]. Let us calculate the imaginary parts of B -+ 71'71' decay amplitudes. In the amplitude pp -+ 71'71' of pp intermediate state in eq.(9) the exchange by pion trajectory in the t-channel dominates. It is determined by the well known constant gP->7r7r' This contribution is the dominant one for B -+ 71'71' decays due to a large probability of B -+ pp-transition. On the contrary 71'71' intermediate state plays a minor role in B -+ pp-decays. In description of 71'71' elastic scattering amplitudes in eq.(9) contributions of P, f and p regge-poles was taken from ref. [15]. Finally 71'a1 intermediate state should be accounted for. Large branching ratio of Bd -+ 71'±ai-decay ( Br(Bd -+ 71'±ai) = (40 ± 4) * 10- 6 ) is partially compensated by small P71'al coupling constant (it is 1/3 of p71'71' one). As a result the contributions of 71' a 1
o
259 intermediate state (which transforms into 7r7r by p-trajectory exchange in tchannel) to PSI phases equal approximately that part of 7r7r intermediate state contributions which is due to p-trajectory exchange. Assuming that the sign of the 7ral intermediate state contribution into phases is the same as that of elastic channel and taking into account that the loop corrections to B -. 7r7r decay amplitudes leads to the diminishing of the (real) tree amplitudes by セ@ 30% we obtain: (10) The accuracy of this prediction is about 15°. For pp final state analogous difference is about three times smaller, og - ッセ@ セ@ 15°. Thus the proposed model for FSI allows us ti explain the B -. 7r7r / B -. pp puzzle. 4
Direct CPV in B -. 7r7r-decays and phases of the penguin contribution
The direct CP-violation parameter C+_ in B -. 7r7r-decays is proportional to the modulus of the penguin amplitude and is sensitive to the strong phases of Ao, A2 and penguin amplitudes. So far we have discussed phases of the amplitudes Ao, A 2. The penguin diagram contains a c-quark loop and has a nonzero phase even in the QCD perturbation theory. It was estimated in ref. [lJ and is about 10°. Note that in PQCD it has a positive sign. Let us estimate the phase of the penguin amplitude op considering charmed mesons intermediate states: B -. DD, 15* D, DD*, 15* D* -. 7r7r. In Regge model all these amplitudes are described at high energies by exchanges of D*(D 2)-trajectories. An intercept of these exchange-degenerate trajectories can be obtained using the method of [16J or from masses of D* (2007) - land D2 (2460) - 2+ resonances, assuming linearity of these Regge-trajectories. Both methods give aD- (0) = -0.8 -;- -1 and the slope 。セB@ セ@ 0.5GeV- 2 . The amplitude of D+ D- -. 7r+7r- reaction in the Regge model proposed in papers [17J can be written in the following form: 2
T DD-->1r7r (s, t) = -
g; e-
i1r
(t)r(l - aD" (t)) (S/ Sed)D" (t)
,
(11)
where r(x) is the gamma function. The t-dependence of Regge-residues is chosen in accord with the dual models and is tested for light (u,d,s) quarks. According to [17J Sed セ@ 2.2GeV 2 . Note that the sign of the amplitude is fixed by the unitarity in the t-channel (close to the D*-resonance). The constant is determined by the width of the D* -. D7r decay: g6/(167r) = 6.6. Using (9) and the branching ratio Br(B -. DD) セ@ 2 . 10- 4 we obtain the imaginary part of P and comparing it with the contribution of Pin B -. 7r+7r- decay probability we get Op セ@ -3.5°.
95
260
The sign of op is negative - opposite to the positive sign which was obtained in perturbation theory. Since D V-decay channel constitutes only セ@ 10% of all two-body charm-anticharm decays of Bd-meson, taking these channels into account we easily get (12) which may be very important for interpretation of the experimental data on direct CP asymmetry. It was shown in ref. [2], that assuming that phases satisfy to the conditions: 00 - 02 = 37°,02 > 0 and 0p > 0, it is possible to obtain the following inequality
C+_ > -0.18.
(13)
The experimental results obtained by Belle [18] and BABAR [19] are contradictory (14) 」Rセャ・@ = -0.55(0.09) , cRセbar@ = -0.21(0.09), Belle number being far below (13). For non-perturbative phase of the penguin contribution (12) the value of theoretical prediction for C+- can be made substantially smaller and closer to the Belle result. 5
Polarizations of vector mesons in B --' VV -decays
Short distance contributions to vector meson production in B-decays lead to a dominance of the longitudinal polarization of vector meson. This is a general property valid in the large MQ- limit due to helicity conservation for vector currents and corrections should be '" mセ@ / mセN@ It is satisfied experimentally in B --' p+p_ decays, where the contribution of longitudinal polarization of p mesons is h = f L/f = 0.968 ± 0.023. On the other hand there are several B-decays to vector mesons, where longitudinal polarizations give only about 50% of decay rates. For example: for B+ --' K*op+ h = 0.48 ± 0.08, BO --' K*opo h = 0.57 ± 0.12, B+ --' ¢K*+ h = 0.50 ± 0.07, BO --' ¢K*o h = 0.491 ± 0.032 [3]. This is a real puzzle if only short distance dynamics for these decays is invoked. First let us note that in all decays, where f L セ@ 50% penguin diagrams give dominant contribution. In this case a large contribution to the matrix elements of decays comes from DDs(D* V., DV;, .. ) intermediate states, which have large branching ratios. The amplitude of the binary reaction DVs --+ VV at high energies is dominated by the exchange of D* -regge trajectory and according to general rules for spin-structure of regge vertices (see for example [20]) final vector mesons are produced purely transversely polarized. Thus we expect a large fraction of transverse polarization of vector mesons in these decays. A value of h is sensitive to intercept of D*-trajectory [21]. If the
261
penguin contribution in the decays indicated above is dominant in the SU(3) limit we have:
and h in all these decays should be the same. These predictions agree with experimental data [3].
6
Puzzle of charm-anticharm baryons production
Large probability of B-decay to Ae3e has been observed recently: Br(B+ -; 3 aエSセ@ rv 10- ) [3]. It is surprisingly large compared to the branching of Bdecay to Atf5 = (2.19 ± 0.8)10- 5 • From PQCD point of view both processes セイ・@ described by similar diagrams with a substitution of ud (for p) by cs (for Be) and phase space arguments even favor p-production. On the other hand from the soft rescatterings point of view large DDs(.D* D s , D D; , .. ) intermediate states, considered in the previous section, can play an important role in B+ -; aエSセM、・」。ケウN@ For Atp final states corresponding two-meson intermediate states have smaller branchings and, what is even more important, have different kinematics. For DDs, .. intermediate states the momentum of these heavy states is not large (p セ@ 1.8GeV) in B rest frame and all light quarks (u, d, d, s are slow in this frame. Final aエSセ@ are also rather slow in the B-rest frame and thus all quarks have large projections to the wave functions of the final baryons. On the contrary for 7r D, pD, .. intermediate states in Atp-decays momenta of ii, d- quarks in light mesons are large and projections to the wave functions of final baryons have extra smallness. The resulting suppression can be estimated in regge-model of ref. [17] with nucleon trajectory exchange in the t-channel and is rv 10- 2 in accord with experimental observation,
7
Conclusions
FSI play an important role in two-body hadronic decays of heavy mesons. Theoretical estimates with account of the lowest intermediate states give a satisfactory agreement with experiment and provide an explanation of some puzzles observed in B decays.
Acknowledgments This work was supported in part by the grants: RFBR 06-02-17012, RFBR 06-02-72041-MNTI, INTAS 05-103-7515, Science Schools 843.2006.2 and by Russian Agency of Atomic Energy.
262
References
[1] [2] [3] [4] [5] [6] [7] [8] [9]
A.B. Kaidalov, M.I. Vysotsky, Yad. Fiz. 70,744 (2007). A.B. Kaidalov, M.l. Vysotsky, Phys. Lett. B652, 203 (2007). HFAG, http://www.slac.stanford.edu/xorg/hfag. M. Gronau, J.L. Rosner, Phys. Lett. B595, 339 (2004). C.-W. Chiang, Y.-F. Zhou, JHEP 0612,027 (2006). CLEO Collaboration, M. Selen et al., Phys. Rev. Lett. 71, 1973 (1993). CLEO Collaboration, S. Ahmed et al., Phys. Rev. D66, 031101 (2002). J.D. Bjorken, Nucl. Phys. (Proc. Suppl.) Bll, 325 (1989). M. Beneke, G. Buchalla, M. Neubert and C.T. Sachrajda, Nucl. Phys. B606, 245 (2001). [10] A. Kaidalov, Proceedings of 24 Rencontre de Moriond "New results in hadronic interactions", 391 (1989). [11] J.P. Donoghue, E. Golowich, A.A. Petrov and J.M. Soares, Phys. Rev. Lett. 77, 2178 (1996). [12] M. Suzuki, L. Wolfenstein, Phys. Rev. D60, 74019 (1999). [13] A. Deandrea et al., Int. J. Mod. Phys. A21, 4425 (2006). [14] H-Y. Cheng, C-K Chua and A. Soni, Phys. Rev. D71, 014030 (2005). [15] KG. Boreskov, A.A. Grigoryan, A.B. Kaidalov, I.I. Levintov, Yad. Fiz. 27,813 (1978). [16] A.B. Kaidalov, Zeit. fur Phys. C12, 63 (1982). [17] KG. Boreskov, A.B. Kaidalov, Sov.J.Nucl.Phys. 37, 109 (1983). [18] H.Ishino, Belle, talk at ICHEP06, Moscow (2006). [19] B.Aubert et ai, BABAR Collaboration, hep-ex/0703016 (2007). [20] A.B. Kaidalov, B.M. Karnakov, Yad. Fiz. 3,1119 (1966). [21] M. Ladissa, V. Laporta, G. Nardulli and P. Santorelli, Phys. Rev. D70, 114025 (2004).
MEASUREMENTS OF CP VIOLATION IN b DECAYS AND CKM PARAMETERS Jacques Chauveau a LPNHE,IN2P3/CNRS, Univ. Paris-6, case courrier 200, -4 place Jussieu, F-75252 Paris Cedex as, Prance Abstract. After a brief review of CP violation phenomenology in the standard model I depict recent measurements of the CKM angles. The emphasis is on the latest determinations of the angle (3 = 1 made using amplitude analyses of threebody final states. The results of the CKM fits to date are used to summarize the talk and put the subject into perspective.
1
CP Violation in the Standard Model
The B factories have established that the Standard Model (SM) accommodates CP violation via the Cabibbo Kobayashi Maskawa (CKM) formalism [1] where the couplings of the W boson to quarks include the elements of the fundamental unitary CKM matrix V. For three generations, V depends on four real parameters, one of which is an irreducible imaginary part that induces opposite sign weak phases for CP-conjugate transitions of quarks and antiquarks. The Wolfenstein parameterization [2], 1 - >-2/2 ->-
A>-3(1 - p - iT})
is the first term of an expansion in the small parameter A = sin Be (Be is the Cabibbo angle). By changing p and T} to 75 and 'fj defined in reference [3], an approximation good to 0(A6) is obtained which is widely used. The unitarity relation between the first and third columns of V is conveniently drawn on Figure 1 as a triangle, the Unitarity Triangle (UT), in the complex plane.
Figure 1: The CKM Unitarity Triangle UT. At 0(>-6), the apex coordinates are (p, 7i). Because of CP violation, the triangle is not squashed to the real axis. Its angles are constrained by CP violation experiments.
1\ .---------
A I
vNョカセ@
iVcdV.t
The apex of the UT has coordinates (75, Yj). Present measurements vindicate the SM with precisions of 0.5% on A, 2% on A, 20% on 75 and 7% on 'fj. These numbers are upper limits to possible New Physics corrections to the flavor sector of ae-mail: [email protected]
263
264 the SM. Such effects are actively searched for in an experimental programme seeking to overconstrain the position of the UT apex from all relevant measurements. In this talk I concentrate on the CP observables and the associated UT angles measurements. On August 21, 2007 the BABAR and Belle experiments had integrated luminosities of 469 and 710 fb -1. A B meson decay B ----> f ex(aJ hibits CP violation when (at least) two paths connect the initial and fib---IC nal states. One distinguishes three kinds of CP violating effects. Direct CP violation decay processes are such that the particle decay rate r(B ----> 1) differs from the antipar(bJ W ticle rate r(B ----> 1). Both neutral and charged B mesons can show b direct CP violation. CP violation in mixing stems from the misalignment of the neutral B CP eigenstates and propagation eigenstates (BH,L ex pBo ± qED, with masses mH,L). This effect which is domiFigure 2: Tree (a) and Penguin (b) b-quark nant for the neutral kaons is small decay diagrams. for the B mesons. Most important is the third category: CP violation in the interference between mixing and decay. The simplest case is a process where a neutral B decays to a CP eigenstate fop. The two paths, B O ----> fop and B O ----> EO ----> fop interfere with differing patterns for initial B O and EO resulting into a time dependent CP asymmetry. For golden modes, these asymmetries do not depend on strong phases and give clean experimental access to UT angles. Neglecting electroweak Penguin diagrams, a b-quark non leptonic decay amplitude (Table 1) is the sum of two terms which can be Tree-like or Penguin-like (Figure 2) and whose relevance is determined by the power of ..\ of their CKM factors. A decay channel where one term is dominant is a golden mode. At the B factories the B mesons are produced exclusively in BE pairs from the Y(4S) decays. The pairs of neutral B mesons are produced in an entangled quantum state. We select neutral pairs where one B mesod' decays to f and the other to a flavor specific mode. We measure 6.t the time difference between the two decays. The time dependent CP asymmetry Af is an oscillatory function of 6.t with a frequency given by the mass difference I::!.m = mH - mL: rBO--->f(l::!.t) - rB°--->f(6.t)
Af(l::!.t) bf
== r-
B0--->(
(6.) t
+ r B0--->f (6.t )
=
. Sf sm(6.m6.t) - C f cos(l::!.m6.t),
is the CP eigenstate, we drop the CP subscript for brevity.
265 . 'Sm>'t C 1-1>'11 2 9:At. . h S j -- 2 1+I>'tI 2 ' j = 1+1>'tI 2 ' and the ratIo Aj = p At whIch compares were mixing and decay amplitudes (Aj, Aj = A(BO, EO --> 1) have been introduced. For a golden mode in the 8M: Cj = 0 (no direct CP violation) and Sj = -7}j sin
sss). New Physics can contribute to the latter via virtual new particles in the loop.
Table 1: CKM structure of non leptonic b decay amplitudes. The amplitude for a b --> qlq-2q3 transition is written in terms of T and/or P amplitudes with the CKM factors shown explicitly. The power of >- governing the first and second terms are given. A golden channel leads to a pure measurement of a CKM phase or UT angle 'P. Only effective phases are accessible from the non golden channels. quark process Aces"" Veb v・セtウ@ + Vub V':sPs Asss "" Veb v・セpウ@ + Vub V':sP; Aced"" Veb Vcd Teed + "lltb '-"t'dPd Auud "" Vub V,:dTuud + Vtb vエセp、@
2
1st term ^Mセ@
>-2 >-3 >-3
2nd >-4 >-4 >-3 >-3
example golden golden
Jj1/J K S,L ¢K£
D+D71"+ 71"- , pO pO
'P f3 f3 f3eff aeff
Recent Measurements of the angle /3
The most recent results are tabulated in reference [3]. Here I focus on the measurements of the b --> ccs and b --> sss channels, in particular on the golden modes. Over the last few years, much speculation was entertained by the observation that most Penguin dominated b --> sss final states were measured with sin2/3ejj lower than those from Tree dominated b --> ccs (Figure 3). A simple minded average of all the Penguin measurements fell lower than the Tree measurement with almost 3 standard deviation significance (Figure 4-b)). Figure 3 shows the latest measurements of aSGーHセエI@ with the golden channels B --> charmonium KO by BABAR [4] and J/1jJKo by Belle [5]: S S
= 0.714 ± 0.032 ± 0.018, C = 0.049 ± 0.022 ± 0.017 (BABAR), = 0.642 ± 0.031 ± 0.017, C = 0.018 ± 0.021 ± 0.014 (Belle),
where the first uncertainties are statistical and the second ones systematic. The average over all charmonium KO measurements is sin 2/3 = 0.678 ± 0.025 or, in the first quadrant of the (p,7}) plane: /31 = (21.3 ± 1.0)0 or /32 = (67.8 ± 1.0)0, /31 being favored by several measurements each with small statistical significance [6]. New this summer are the time dependent amplitude (Dalitz) analyses on Penguin golden channels kセィK@ h- [7,8], where h refers to a 7r or a K meson.
888
Penguin channels.
direct measurements of the f3 (not a function final states as well as the non-resonant threeAfter "ll'OICl.l1lC, I focus on the
are paraman isobar model. Each term is a ",,"ull.teA COmI)lCX (isobar) coefficient whose argument incor5 a)-c) show the two-body invariant and the components from ^iBLNイョQセーᄋG@ for the
enriched fit distributions for the time dependent Dalitz analysis of . The full fit distributions are superimposed over the data points three invariant mass spectra of the Dalitz plot. The shaded areas correspond to the background components, and the signal. Vetoes create holes the D and J /'Ij; The pO and fo peaks are in the 7r+7rThe corresponding dependent CP asymmetries for d) and are shown at the bottom of the
which makes the minded average sin over with the measurements from the Tree processes the result from the above pre4 to the older dataset 4
'AJ.tll,Jel>L,lUJlC
and measured B meson related There is no evidence for direct OP violation from the measured time
268 dependent CP asymmetries and no compelling hint for New Physics. 3
Recent Progress on the other UT Angles
Here, I have chosen to highlight the recent progress made on the GronauLondon (GL) analysis [9] of the B -+ pp channels. This charmless b -+ uud decay is not a golden mode (Table 1). The Penguin pollution introduces a phase shift on the determination of the UT angle a and one measure ael I instead of a. The GL method exploits the SU(2) symmetry to combine all charge states in B -+ pp and determine a-aell up to trigonometric ambiguities. It has been appreciated for some time that since the branching fraction for BO -+ pO pO is measurable with fair accuracy, the GL triangle can be constructed more precisely than in the founding case B -+ 7r7L Furthermore with four charged pions in the final state, the decay vertex can be accurately reconstructed and the time dependent CP asymmetry measured, an impossible feat for B -+ 7r 0 7r 0 . With high statistics it has been possible this year to measure Acp(t) for the longitudinally polarized pOpo pairs [10]. Including these results into the GL fit yields the confidence level profile for a - ael I shown on Figure 6. It is nomore fiat as was the case when no CP asymmetry measurement was included. Some discrimination between the mirror solutions already observed with previous spin-averaged measurements of Acp(t) can be seen. There is hope that an accurate determination of a will be obtained with the full data samples of the B factories.
Figure 6: Exclusion confidence level scan for Q The red (solid) QeJ J. curve corresponds to the recent measurement of the time dependent asymmetry for longitudinally polarized pO pO pairs in neutral B decays [10]. The one and two-sigma exclusion levels are shown as horizontal intermittent lines.
4
セ@
-!
1 ••••••. without cセq@
0.8
and sセ@
with Cro and without sセ@
0 .•
0.4
0.2
·10
10
20
30
40 «- 7r+ 7r- e± v decay is described by the five CabibboMaksymowicz variables [13]: invariant mass squared of a dip ion Sn = M;n' invariant mass squared of dilepton Sn = M;v and angles en, ee, ¢. en is the angle between 7r- and dilepton momenta in the rest frame of dipion, ee is the angle between v and dip ion momenta in the rest frame of dilepton. ¢ is the angle between the plane of dilepton and e± momenta and the plane of dipion and 7r+ momenta in the kaon rest frame. The matrix element is defined by means of axial form factors F,G and a vector form factor H. A partial wave expansion of the form factors may be restricted to sand p waves: F = Fs ei08 + FpeiOpcosen, G = Gpe iOp , H = Hpe iOp (only phase shift 5 = 5s - 5p is observable). From the 2003 data, about 670000 Ke4 decays have been selected. Reconstructed events are distributed in 10 x 5 x 5 x 5 x 12 iso-populated bins in the (M1r1r' Mev, cos(e n ), cos(ee), ¢) space. Ten independent fits (one per M1r1r bin) of five parameters (Fp, Gp, Hp, 8, and a normalization constant, that absorbs Fs) where performed in four dimensional space using the acceptance and resolution information from Monte Carlo simulation. The value of the phase difference 5 was extracted from the measured asymmetry of ¢ distribution as a function of M 1r1r . The result of 5 measurement is shown on the Fig. 3 together with results from previous experiments [2,3]. The phase shift measurements can be related to the 7r7r scattering lengths using the analytical properties and crossing symmetry of amplitudes (Roy equations [15]). One can use the Universal Band approach [16,17] to extract alone. At the center line of the Universal Band (I-parameter fit), NA48/2 = 0.256±0.006stat±0.002syst±0.018theoTl phase measurements translate as which implies a6 = -0.0312 ± O.OOl1 stat ± 0.0004 syst ± 0.013 t heor. In the case of the fit where both ag and a6 are free parameters, the result is ag = 0.233 ± 0.016 stat ± 0.007 syst, a6 = -0.0471 ± O.Ol1 stat ± 0.004 syst (the correlation is 96.7%). Finally, resent work [18] suggests that isospin symmetry breaking effects, neglected so far in the Ke4 phase shift analysis, would lead, when taken into account, to decrease of ag by セ@ 0.022, and a6 - by about 0.004, leading to good compatibility between the Ke4 and cusp analyses results for pion scattering lengths.
ag
ag
284
•
,.-....0.3 ""0
t: 0.2
セ@
'0
•
0
-0.1
t •• t ., • t • •
. • •
0 .1
• NA48/2 (2003 Data) • E865 [3] ... Geneva-Saclay [2]
'
セGMLi@
0.28
0.3
•
0.32
0.34
0.36
0.38
M",,( GeV/ c Figure 3: Phase shift 8 measurements from
5
Ke4
0.4
2 )
experiments
Conclusion
Two independent results of 7r7r scattering lengths measurement, obtained by NA48/2 experiment, are compatible between each other and are in agreement with current predictions of ChPT, if the isospin symmetry breaking effects are taken into account in both analyses of experimental data. References
[1] G.Colangelo, J.Gasser, H.Leutwyler, Nucl.Phys. B 603, 125 (2001). [2] L.Rosselet et al, Phys.Rev. D 15,574 (1977). [3] S.Pislak et ai, Phys.Lett. 87,221801 (2001). [4] B.Adeva et al, Phys.Lett. B 619, 50 (2005). [5] J.RBatley et al, Eur.Phys.J. C 52, 875 (2007). [6] V.Fanty et al, Nucl.lnstrum.Methods A 574, 433 (2007). [7] J .RBatley et ai, Phys.Lett. B 633, 173 (2006). [8] N.Cabibbo, Phys. Rev. Lett. 93, 121801 (2004). [9] N.Cabibbo and G.Isidori, JHEP 503, 21 (2005). [10] K.Knecht and RUrech, Nucl.Phys. B 519, 329 (1998). [11] Z.K.Silagadze, JEPT Lett 60,689 (1994). [12] S.RGevorkyan, A.V.Tarasov, O.O.Voskresenskaya. Phys.Lett. B 649, 159 (2007). [13] N.Cabibbo and A. Maksymowicz, Phys. Rev. 168, 1926 (1968). [14] G.Amoros and J.Bijnens, J.Phys G 25, 1607 (1999). [15] S.Roy, Phys. Lett. B 36, 353 (1971). [16] B.Ananthanarayan et al, Phys.Rep. 353, 207 (2001). [17] S.Descotes, N.Fuchs, L.Girlanda, J.Stern, Eur.Phys.J. C 24, 469 (2002). [18] J.Gasser, Proc. of KAON 2007 Int. Conf., Frascati, May 21-25, (2007).
RARE KAON AND HYPERON DECAYS IN N A48 EXPERIMENT N.Molokanova U
Joint Institute for Nuclear Research, 141980 Dubna, Russia Abstract. Recent results from the experiments NA48/1 and NA48/2 are reported. The first measurement of direct emission and interference terms in K± --+ 7l'±7l'0')' and the first observation of K± --+ 7l'±e+e-')' are described. Concerning NA48/1 measurements on radiative hyperon decays are presented.
1
Introduction
The series of experiments NA48 have explored many topics in the charged and neutral kaon physics. In this paper we shall discuss some of the most recent measurements produced by two stages of the experimental program: NA48/1 and NA48/2. NA48/1 (2002) has been oriented mainly to the study of rare Ks decays and has produced also results in hyperon physics. NA48/2 (2003-2004) was designed to search for direct CP-violation in K± decays, but also many other results in rare decays have been achieved.
2 The radiative K The decay channel K± ----t 7f±7f0'f' is one of the most interesting and important channels for studying the low energy structure of the QCD. Three components contribute to K± ----t 7f±7f0'f' decay amplitude: the Inner Bremsstrahlung (IB) associated with the decay K± ----t 7f±7fo in which the photon is emitted from the outgoing charged pion, Direct Emission (DE) from the vertex and the interference (INT) between these two. The K± ----t 7f±7f0'f' decays are described in terms of two kinematic variables: the kinetic energy of charged pion in kaon rest frame (T;) and invariant variable W 2 = (PK . P",!)(P7l' . P"'!)/(mKm 1r )2, where PK , P1r , P",! are the 4-momenta of the kaon, charged pion and odd gamma, respectively. About 124.103 events were selected in the range T; < 80 Me V and 0.2 < W < 0.9. In the previous measurements a lower cut T; > 55 MeV was introduced in order to suppress K± ----t 7f±7fo7fo and K± ----t 7f±7fo background. In NA48/2 measurement these backgrounds are avoided by application of a special algorithm, which detects overlapping gamma in the detector and due to the limit ±10 MeV on the deviation ofreconstructed kaon mass from its nominal value. The upper cut on T; rejects K± ----t 7f±7fo decays. The background in the selected sample is kept under 10- 4 . The probability of the photon mistagging (i.e. choice of wrong odd photon) is estimated to be less than 0.1%. ue-mail: [email protected]
285
The preliminary Yalues for the fractions of DE and INT with respect to IB are Frac(DE) = (3.35 ± 0.35 stat ± Q.25syst)% Prac(INT) = (-2.67 ± 0.81 stat ± 0.73^,*)%This is the first measurement of a non vanishing interference term in the K^ —»• 7T 7r0/y decay. 3
First observation of the decay K^ —* ir ± e + e~7
NA48/2 experiment observed for the first time the radiative decay K^ —> 7r ± e + e~7. The signal is selected between 480 MeV/e2 and 505 MeV/c2 in the invariant ir : t e + e"7 mass and requiring the invariant e + e^7 mass to be greater that 260 MeV/e2. Fig.l displays the projections of this region on the corresponding axes. The crosses represent data while the filled distribution represent different simulated background contribution. 120 candidates were selected with 7.3 ± 1.7 estimated background. The main source of BG is the K —> 7r^~ir(L'y with a lost •*¥.
Figure 1: K~^ —• it^ze^~e~~ry decay. The invariant w^e^e y (left) and e"*"e 'y (right) masses with corresponding background distributions. Black crosses represent data distribution.
By using K^ ^ w^w0 as normalization channel the branching ratio was pr€:nnnnl:try est,lmatE:C1 to be Br{K± -* W±TT°'J) = (1.19 ± 0.12stet ± 0.04,v.t) • 10^8. More details on If* —* w±e+e~'y decay analysis could be found in [1], 4
Weak radiative H° decays
Up to this day weak radiative hyperon decays as H° —> A7 and E° —* S7 are still barely understood. Several theoretical models exist, which give
287
very different predictions. An excellent experimental parameter to distinguish between models is the decay asymmetry a. It is defined by HN _ = *0(l4W), where 9 is the direction of the daughter baryon with respect to the polarization of 5° in its rest frame. For example, the decay asymmetry for H° —» A7 can be measured by looking at the angle between the incoming 5 and the outgoing proton from the subsequent A —> pir^ decay in the A rest frame. Using this method, the measurement is independent of the unknown initial H° polarization. The NA48/1 experiment has selected 48314 5° -+ A7 and 13068 H° -* £7 candidates (fig,2). The background contributions are 0.8% for H° —•> A7 and about 3% for S° —•» S7, respectively.
Figure 2: H° —•> A"/ (left) and H° —+ £7 (right) signal together with MC expectations for signals and backgrounds.
Using these data, fits to the decay asymmetries have been performed. In case of H° —* £ 7 , where we have the subsequent decay E° —+ A7, the product cos0s~-*"£>y • cosOs-tAi n a s to be used for the fit. Both fits show the, expected linear behavior on the angular parameters. After correcting for the well-known asymmetry of A —» pn~, values of a H o^A 7 = -0.684 ± 0.0203tet ± 0.061 s v s t and as^s-y = ^0.682 ± 0.031 s t a t ± 0.0653I,st are obtained. These values agree with preYious measurements by NA48 on H° ^+ A7 [2] and KTeV on H° —* £7 [3], but are much more precise. In particular the result on S° —> A7 is of high theoretical interest, as it confirms the large negative value of the decay asymmetry, which is difficult to accommodate for quark and vector meson dominance models.
288
5
First observation of 3° —- - +
la the 2002 run of NA48/1 experiment the weak radiative decay E° ~~> Ae+e~~ was detected for the first time [4]. 412 candidates were selected with 15 C:1CgroulUO events (fig. 3) The obtained brancb:ing fraction Br(E° ~* Ae + e") = (7.7 ± 0.5 stot ± 0Asyst) • HP 6 is consistent with inner bremsstrahlung-like e+e~ production mechanism.
Figure 3: The invariant mass of Ae+e-
together with the simulated background.
The decay parameter ctEAee c a n be measured from the angular distribution dN N ^^^YCl-CHAee^COS^H), (1) where cosffps is the angle between the proton from A —» JM decay relative to the H° line of flight in the A rest frame and a_ is the asymmetry parameter for the decay A —> pw^. The obtained value aSAee = -0.8 ± 0.2 is consistent with the latest published value of the decay asymmetry parameter for 5 —> A-y. References [1] [2] [3] [4]
J.R.Batley et al, CERN-PH-EP/2007-033, accepted by Phys.Lett.B. A.Lai et al, Phys.Lett. B 584, 251 (2004). A.Alavi-Haxati et al, Phys.Rev.Lett. 86 , 3239 (2001). J.R.Batley et al, Phys.Rev. B 650, 1 (2007).
THE K+ -
rr+ vi) EXPERIMENT AT CERN Yu.Potrebenikov a
Laboratory of Particle Physics, Joint Institute for Nuclear Research, 141980 Dubna Moscow region, Russia Abstmct. The P326 proposal of a new experiment NA62 aiming to perform precise measurement of the very rare kaon decay K+ -+ 7I"+vii branching ratio at CERN is described. About 80 K+ -+ 71"+ vii events with 10% of background is planned to obtain in two years of data taking. The status of the project, current status of R&D and future plans of the experiment are discussed.
1
Introduction
The K+ -) 7r+vv decay is a flavor changing neutral current process, computable with very small theoretical uncertainty of about 5% [1]. The hadronic matrix element can be parameterized in terms of the branching ratio of the well measured K+ -) 7r°ev decay [2] using isospin symmetry. The computed value is (8.0 ± 1.1) x 10- 11 , where the error is dominated by the uncertainty in the knowledge of the CKM matrix elements. Such an extreme theoretical clarity, unique in K and B physics, makes this decay (together with KL -) 7r°vv) extremely sensitive to new physics (see for example [3,4]). Only 3 K+ -) 7r+vv events have been observed by BNL-E949 experiment [5], that gives a central value of the branching ratio higher than the SM expectation. But rv 10% accuracy measurement of the branching ratio is required to provide a significative test of new physics contributions. This is the goal of the proposed NA48/3 (or NA62) experiment at CERN-SPS [6]. The aim of the experiment is to collect about 80 K+ -) 7r+vv events with the background level of 10%. 2
Proposal of the future experiment
The NA62 experiment will use kaon decays in-flight technique, based on the NA48 apparatus and the same CERN-SPS beam line which produced the kaon beam for all NA48 experiments. The R&D program for this experiment, started in 2006, is continuing in 2007. The data taking should start in 2011. The layout of the experiment is shown in fig. 1. The goal of the experiment can be reached by having 10% signal acceptance and by using a beam line able to provide the order of 10 13 kaon decays. To study K+ -) 7r+vv decay it is necessary to reconstruct one positive pion track in the downstream detector. If a beam and a pion tracking detectors provide a precise reconstruction of the decay kinematics, the missing mass allows a kinematical separation between the signal and more than 90% of the total background (fig.2); only non-gaussian tails from K+ -) 7r+7r0 and K+ -) p,+vJ.L ae-mail: [email protected]
289
290 m
\(,\'IU)
LMセG@
MLケセュ@
ュu\iセ⦅@
VACUUM
セ@
MGiセ
---0-
1(+-75GoV
iL-_ _ _ _---,
-1
SI'IIlES.l
S.\C
-\
セ[Zi。エュ@
r:,
',I: "
: :: :: : IStraw "
-2
,\,>
•.
--LKr
" .., Tube
Figure 1: Layout of the experiment
in the squared missing mass resolution will present in the defined signal region. But the kinematics only cannot provide background rejection factor of 10 13 . So, different veto (photon and muon) and particle identification (CEDAR and RICH) systems are included into experimental set-up to fulfill these needs. Moreover, the detector can provide redundancy both for kinematics reconstruction and particle identification allowing to estimate background directly from the data.
MoNiGsAZ\⦅ヲLセBョッォウ[f]Dclゥ@
BGMNセoQU@ セsAゥ@
NoセGUBMゥWL][イPーjlZャA@ GeV2/c
4
MlセoBQU@ ュセャウD@
GeV 2/C 4
Figure 2: Squared missing mass for krum decays
2.1
The beam line
A 400 GeV Ic proton beam from the SPS, impinging a Be target, produces a secondary charged beam. 100 m long beam line selects 75 Ge V I c momentum
291
beam with 1.1 % RMS momentum bite and an average rate of about 800 MHz integrated over an area of 14 cm 2 • The beam contains 6% of K+. The average rate seen by the downstream detectors integrated on their surface is rv 11 MHz. The described beam line provides 5 x 10 12 K+ decays, assuming 60 m decay region and 100 days of run at efficiency of 60%, which is a very realistic estimation based on the decennial NA48 experience at the SPS.
2.2
The experimental set-up and RfjD current status
The experimental set-up consists of: Beam (Gigatracker) and pion (magnetic) spectrometers. The first one consists of three silicon pixel stations across the second achromat of the beam line, produced by 300 x 300 /-lm2 pixel each. The time resolution of 200 ps is provided by 0.13 microns technology of silicon detector production. The magnetic spectrometer is designed with 6 (or 4) straw chambers with 4 coordinate views each. Chambers should work in vacuum, introduce small material contribution (0.5% Xo per chamber) and have a good spatial resolution (130 microns per view). 36 /-lm mylar straw tubes with about 10 mm in diameter welded by ultrasound machine and cowered with gold inside will be used for these reasons. This spectrometer will be used as a veto as well for high energy negative pion from Ke4 decays. The R&D program has been started in 2006, a full length and reduced-size prototype has been constructed, integrated and tested in the NA62 set-up during the 2007 run at CERN. Differential Cherenkov counter CEDAR and RICH. CEDAR [7], differential Cerenkov counter existing at CERN, will be used after its upgrade for new experimental conditions for kaon tagging to keep the beam background under control. The 18 m long RICH located after magnetic spectrometer and filled with Ne at atmospheric pressure aimed for particle identification and pion momentum measurement. It will contain about 2000 PMTs in the focal plane and has to reach a time resolution of 100 ps to provide time information for downstream tracks. A full-length prototype 60 cm in diameter and 96 PMTs has been integrated in the NA62 set-up and tested during the 2007 NA62 run at CERN. Large angle (for 10-50 mrad), medium angle (for 1-10 mrad) and small angle (for
0.28
セ@
0.26
1 2
3 4 5
Q)
LO
0.24
6
"
t-
0.22 0.2 0.18 0.16
+
""
Cl..
V
0.14
Oセ@
.....................................•..........
0.12 0.1
o
20
40
60 Shh 1/2,
80 [GeV]
100
120
140
Figure 2: Average square for the transverse momentum of K+-meson produced from the interaction of two hadrons one of them is in the equilibrated fireball as a function of "fShh at T = 150 MeV.
< pセK@
,t ^セL@ respectively, when IC > > Iq , whereas the curves 3 and 4 correspond to the same quantities with IC = 3 1q . The line 5 in Fig.2 corresponds to the average square for the transverse momentum of K+ produced in the free p + p collisions < p; ^セイ]@ 0.14 GeV/c 2 . As our calculations show, the temperature dependence for < pセKLエ@ ^セエ@ is rather weak in the interval T = 100 - 150 MeV.
As is evident from Fig.2, the obtained results are sensitive to the mass value of a hadron which is locally equilibrated with the surrounding nuclear matter at ..jShh :::; 10(GeV). We found that the quark distribution in a hadron depends on the fireball temperature T. At any T the average transverse momentum squared of a quark grows and then saturates when ..jShh increases. Numerically this saturation property depends on T. It leads to a similar energy dependence for the averThe saturation age transverse momentum squared of hadron hI < pt,t ^セエN@ property for < ーセ@ 1, t ^セエ@ depends also on the temperature T and it is very sensitive to the dynamics of hadronization. As an example, we studied the energy dependence of the inverse slope of transverse mass spectrum of K-mesons produced in central heavy-ion collisions and got its energy dependence qualitatively similar observed to one experimentally. We guess that our assumption on the thermodynamical equilibrium of hadrons given by eq.(l) can be applied for heavy nuclei only and not for the early interaction stage.
317
AcknowledgIllents
The authors are grateful for very useful discussions with P.Braun-Munzinger, K.A.Bugaev, W.Cassing, A.V.Efremov, M.Gazdzicki, S.B.Gerasimov, M.I.Gorenstein, Yu.B.Ivanov, A.B.Kaidalov and O.V.Teryaev. This work was supported in part by RFBR Grant N 05-02-17695 and by the special program of the Ministry of Education and Science of the Russian Federation (grant RNP.2.1.1.5409). References
[1) L.Ahle et. at., E866 and E917 Collaboration, Phys. Let. B476, 1 (2000); ibid. B490, 53 (2000). [2) S.V.Afanasiev et at. (NA49 Collab.), Phys.Rev. C66, 054902(2002); C. Alt et al., J. Phys. G30, S119 (2004); M.Gazdzicki, et at., J. Phys. G30, S701 (2004). [3) C.Adleret at., STAR Collaboration, nucl-ex/0206008; O.Barannikova et at., Nucl. Phys. A715, 458 (2003); K.Filimonov et at., hep-ex/0306056; D.Ouerdane et at, BRAHMS Collaboration, Nucl. Phys. A715,478 (2003); J.H.Lee et at., J. Phys. G30, S85 (2004); S.S.Adler et at., PHENIX Collaboration, nucl-ex/030701O; nuclex/0307022. [4) E.V.Shuryak, Phys. Rep. 61, 71 (1980). [5) E.V.Shuryak and O.Zhirov, Phys. Lett. B89, 253 (1980); Yad. Fiz. 28, 485 (1978) [Sov. J. Nucl. Phys. 28,247 (1978). [6) L. van Hove, Phys. Lett. B118, 138 (1982). [7) M.Gorenstein, M.Gazdzicki and K.Bugaev, Phys. Lett. B567, 175 (2003). [8) B.Mohanty, et at., Phys. Rev. C68, 021901 (2003). [9) M.Gazdzicki et at., Braz. J. Phys. 34, 322 (2004). [10) J.Kuti and V.F.Weiskopf, Phys. Rev. D4, 3418 (1971). [11) G.I.Lykasov, A.N.Sissakian, A.S.Sorin, D.V.Toneev, in preparation. [12) A.Capella, V.J.Tran Than Van, Z.Phys.ClO, 249 (1981). [13) O.Benhar, S.Fantoni, G.I.Lykasov, N.V.Slavin, Phys. Rev. C55, 244 (1997). [14) G.'t Hooft, Nucl. Phys., B72, 461 (1974). [15) G.Veneziano, Phys. Lett., B52, 220 (1974). [16) A.B.Kaidalov and K.A.Ter-Martirosyan, Phys. Lett. B117, 247 (1982). [17) A.B.Kaidalov and O.I.Piskunova, Z. Phys. C30, 145 (1986). [18) A.Capella, U.Sukhatme, C.L.Tan, J. Tran Thanh Van, Phys.Rep. 236, 225 (1994). [19) G.I.Lykasov and M.N.Sergeenko, Z. Phys. C70, 455 (1996).
STRINGY PHENOMENA IN YANG-MILLS PLASMA V.1. Zakharov a
INFN, Sezione di Pisa, Largo PontecoTVo 3, 56127, Pis a, Italy ITEP, B.Cheremushkinskaya 25, Moscow, 117218, Russia Abstract. We review the grounds for and consequences from the hypothesis that at the point of the confinement-deconfinement phase transition both electric and magnetic strings are released into the Yang-Mills plasma. We comment also briefly on the averaged Polyakov line as an order parameter of the deconfinement phase transition.
1
Introduction
The goal of this talk is to substantiate a phenomenological stringy picture for the confinement-deconfinement phase transition. The stringy picture for the phase transition was advocated first long time ago [1] and the topic is, in its generality, too broad for such a talk. Thus, we will concentrate on a recent proposal [2,3] that there exists a magnetic component of the Yang-Mills plasma at temperatures close and above the critical temperature Te. While the main ideas are presented in the original papers [2], there appeared most recently results of dedicated lattice measurements [4,5] which support the picture proposed although much more remains to be done before one could really claim observation of the magnetic component of the plasma. Electric strings
2 2.1
Action vs entropy factoTs
Consider quark and anti-quark separated by distance x. To make the construct gauge invariant one has to connect the quarks by a string: (1)
The path-ordered exponent is our first image of what we would call electric string. If quarks develop in time, the string sweeps an area A. Let us consider the most primitive dynamics of a closed string. The string carries color charge and, therefore has a divergent self-energy. To regularize this divergence, introduce finite thickness of the string, TO , TO « Ixl. Then the corresponding action is of order bare Sstring
=
CIg 2(TO )Aj TO2
=
O"bare'
A
.
(2)
To evaluate the renormalized, or physical string tension O"ren one has to subtract from (2) the entropy factor (see, e.g., [6]): ae-mail: [email protected]
318
319
where Nstring is the number of various surfaces with the same area constant C2 is of pure geometrical origin. As a result b:
A,
(3) the
(4) Consider first ro = a, where a is the lattice spacing. In the limit of the large coupling, g2(a) » 1, the bare action factor prevails and the renormalized tension is positive. We have the strong-coupling confinement. This string is infinitely thin but theory is not realistic because of the strong-coupling limit. In the asymptotic-freedom case, g2(a) -+ 0 the tension (4) is negative and the string is unstable in the ultraviolet. In the ultraviolet, on the other hand, free gluons is the right approximation and strings with a negative tension is not a viable alternative. Next, we can still consider the asymptotic-freedom case but choose the thickThen g2(ro) can be large enough to make the ness of the string ro rv aqセdG@ renormalized tension (4) positive. Thus, we might have 'thick' strings which could be useful effective degrees of freedom in the infrared. At large temperatures g2 is limited by g2 (T), limT -+00 g2 (T) -+ 0 since the time extension of the lattice (Euclidean space-time) is liT. Thus, at an intermediate temperature the effective tension (4) vanishes and the electric strings percolate through the vacuum. 2.2
The Polyakov line
Continuing with the finite-temperature physics, another image for the electric strings is provided by the the Polyakov line which is a Wilson line winding once through the lattice in the periodic time direction:
r
llT
P == Trn
=
TrPexp}o
Ao(x,r)dr,
(5)
where the trace is taken in the fundamental representation. Imagine that we would like to use the Hamiltonian formalism and gauge Ao = O. Unlike the case of T = 0 it is not possible to fix Ao = 0 because of the periodicity in the time direction. In other words, the non-local variable (5) is gauge invariant and cannot be eliminated by gauge transformations. It is still possible to put Ao = 0 provided that the non-local degree of freedom (5) is added explicitly [1] into the partition function:
Z[n] = b Actually,
J
DAn(x,r)exp ( -
J、SクイH。セォIRKfヲャ@
we oversimplify the estimate of the entropy greatly, see, in particular, [7].
(6)
320 where Ak(x, (3) = n- 1Adx, O)n + n-10kn(X). Note, however, that by introducing a new variable we admit extra ultraviolet divergences into the theory and make the model non-renormalizable, for further references see, e.g., [8]. 3
3.1
Magnetic strings
Topology of the magnetic strings
In Yang-Mills theories, one expects that the magnetic strings are no less fundamental than electric strings. Moreover, condensation of magnetic degrees of freedom is commonly believed to be responsible for the confinement. The scenario is realize in the Abelian case, [9]. The magnetic degrees of freedom are identified in this case through violations of the Bianchi identities:
(7) where j::,on is the monopole current. In the non-Abelian case, the gauge potential can be expressed in terms of the field strength tensor [10]:
(8) where gセャ@ is the matrix inverse to the matrix of the field strength tensor. As far as (8) holds, the Bianchi identities are valid automatically. There might exist, however, such field configurations that the inversion (8) is not possible because the matrix G- 1 does not exist. Actually, it was noted from the very beginning [10] that the inversion (8) fails in 2d case, see also below. Alternatively, in 4d case there can exist 2d defects [11] along which the matrix G- 1 is singular. These 2d defects is our image for the magnetic strings. Magnetic strings are to be added as new degrees of freedom to the standard YM theories which assume Bianchi identities valid. 3.2
Surface operators, monopoles
The action associated with the 2d defects can be readily guessed on symmetry grounds. In fact, such surfaces were considered, for other reasons, in Refs. [12,13] (in the latter reference they were labeled as surface operators). Namely, consider a surface, with area element da 1"'-' and introduce the action: S s'ur face
= const
J jQNカgセ@ da
(no summation over
j-l,
v) .
(9)
The central point is that the action (9) respects non-Abelian invariance despite of the fact that it apparently carries a color index a. The reason is that one can
321
use gauge invariance to rotate one particular component of the field strength tensor to the Cartan subgroup:
(10) where for simplicity we considered the gauge group SU(2). In other words, non-Abelian fields living on a surface are in fact Abelian. The inversion (8), on the other hand, is specific for the non-Abelian case and fails in the Abelian case. Thus, the magnetic strings replace the magnetic monopoles (7) relevant to the Abelian case. It is worth emphasizing that to carry a finite magnetic flux the surfaces (9) are to be endowed with singular fields gセカN@ Note that gauge fixation (10) fails if gセカ@ = o. Such defects are trajectories living on the surfaces and correspond to non-Abelian monopoles, for related discussion see [14].
3.3
Dual pictures of confinement
There is a deep relation between magnetic and electric strings. Namely, the expectation value of the Wilson line, < W > can be evaluated either in terms of electric strings open on the heavy quarks, or in terms of the linking number between electric and magnetic strings, [15,16]. It is useful to start with 3d and consider a tube of magnetic field which pierces a surface spanned on the Wilson line. Considering, for simplicity, the Abelian case one gets for the Wilson line:
exp(ifAJ.!dxJ.!)
=
exp(i セ@
exp (- Aminacon/) ,
(12)
where Amin is the minimal area spanned on the Wilson line. One can say that (12) means that the expectation value of the Wilson line is suppressed in the strongest possible way. To get such a suppression the magnetic flux carried by the magnetic strings is to be random [17]. This, in turn, implies that the magnetic strings percolate through the vacuum. For this to happen, the magnetic strings are to have a vanishing tension, (13) amagn = O. Eq. (13) means that the heavy-monopole potential is not confining, as it should be.
322 It is remarkable that we derived (13) starting with consideration of the Wilson line, not directly of the 't Hooft line. 4
Extra dimensions
The logic outlined in the preceding sections has a weak point since we mix up two different pictures for the confining string, that is, thin and thick strings. Indeed, the string which can be open on quarks is to be infinitely thin since quarks are point-like while the string which has tension in physical units, see Eq (4) has thickness of order aqセdN@ This inconsistency is in fact difficult to remove and the way out which is becoming common nowadays introduces a novel notion of extra dimensions, or running string tension, for review see [18]. Roughly speaking, one is assuming the string to be infinitely thin but with tension depending on its size. For areas A :S aqセdG@ (Jeff
rv
I/A
(14)
For larger areas, the string tension is frozen, (Jeff
セ@
(Jeanf
,
if A :::: aqセd@
,
(15)
where (Jeanf determines heavy-quark linear potential at large distances. Formulae (14), (15) are somewhat loose because area is not the only characteristic of a surface. It turns out that language of extra dimensions is much more adequate. In this framework, one postulates that there exists an extra dimension, z such that 'our' world corresponds to z = 0 while strings connecting quarks extend into z =I o. The action associated with the string is the same Nambu-Goto action which we actually discussed above but now the area is calculated with account of geometry which is a nontrivial function of z. In particular, assuming that the metric is (16) where R2 is a constant and Xi ,i = 1, .. ,4, are Euclidean 4d coordinates, one reproduces Coulomb-like heavy-quark potential. This is quite obvious from dimensional considerations and the metric (16) realizes the assumption (14). Concerning realization of (15) it is much more arbitrary since one introduces by hand a new parameter, AQCD . The following model
R2 2 ds = exp(cz 2 ) 2" (Jdt 2 +dx; +r1dz2), f(z) = 1-(nzTe)4, c セ@ z
GeV 2,
(17) gives a reasonable description of broad variety of phenomena both at zero and finite temperatures [19].
323
As for the magnetic strings, they have another geometry and correspond to branes wrapped on extra compact dimensions, which are to be added to the five dimensions already introduced, for details see [18]. Magnetic monopoles, in this language, are Kaluza-Klein modes associated with the extra compact dimensions [11].
5
Stringy phenomena near the critical temperature
After all these preliminary remarks we are in position to make predictions specific for the string-based phenomenology of Yang-Mills theories.
5.1
Polyakov line as an order parameter
As argued first in Ref. [1], in pure Yang-Mills case (without quarks) the expectation value of the Polyakov line (5) serves as an order parameter:
(P) == 0 if T < Te .
(18)
In the explicit calculations [19] with the metric (15) the averaged Polyakov line exp( -constjT) contains at small temperatures exponentially small terms < P ^セ@ and Eq. (18) does not hold. Although non-observance of (18) could well be a consequence of the approximations made, it might be useful to understand the reasons for this discrepancy. The proof of (18) exploits the center symmetry. Namely, the Polyakov line is changed by a phase factor under transformations belonging to the group center of the gauge group while the lattice Yang-Mills action can be formulated as symmetrical under the center transformations. However, the lattice action might not know about the center symmetry as well, (for recent discussion and references see [20]). There is no center-group symmetry in the stringy approach, based on (15) but probably there is nothing wrong about this. Thus, violations of (18) seemingly cannot be ruled out on general grounds. There are further interesting issues to discuss in this connection. In particular, the stringy formulation (15) leads to qualitative predictions which are in accord with the lattice data [22], like fast growing entropy in the system of heavy quarks towards T = Te. On pure theoretical side, dependence of continuum physics on details of the lattice regularization (whether we have the center symmetry or not) is most challenging. Because of space considerations, we cannot go into detailed discussion of these issues here, however.
5.2
Magnetic component of the Yang-Mills plasma
We have already mentioned that at the point of the phase transition, Te one expects [1] vanishing tension of the electric string:
(Jeleetr(T) 2: 0,
T 2: Te
(19)
324 On the other hand, tension of the confining string can be evaluated in terms of the magnetic strings, see subsection 3.3. Thus, Eq. (19) implies that magnetic strings acquire non-zero tension at T > Te:
(J"magn(T) 2: 0, T 2: Te .
(20)
Thus, in the deconfining phase the magnetic strings correspond to physical degrees of freedom and are to be present in the Yang-Mills plasma [2]. The question is, how to detect this effect. On the lattice, magnetic strings are identifiable directly, for details see [11]. And, indeed, the magnetic strings do not percolate at T > Te, for references see [15]. More quantitative predictions can be made in terms of the monopoles, which are, as explained above, particles living on the strings. The word 'particles' is to be perceived with some caution, however, since we are discussing now the lattice, or Euclidean formulation and the difference between virtual and real particles is not so obvious as in the Minkowski space. Nevertheless, one can argue [2] that the density of real (in the Minkowskian sense) particles is proportional to the density of the so called wrapped trajectories [21] which are trajectories stretching in the time direction from one boundary to the other:
Preal(T) '" Pwrapped(T) , T
> Te.
(21)
This relation implies, in turn, that the density pwrapped is to be in physical and cannot depend on the lattice spacing. This is in fact a very units, '" ゥ|セcd@ strong constraint on the data. Which indeed turns to be true [5].
5.3
Ghost-like matter
Measurements on the magnetic strings, reveal [4] astonishingly enough, that both energy density and pressure associated with the magnetic strings are negative: (22) tmagn(T) < 0, Pmagn(T) < 0, Te < T < 2Te . There is a proposal [23] how to accommodate this observation within the stringy picture. The basic idea is that in 2d and 4d the conformal anomaly has opposite signs and this is responsible for the ghost-like sign in case of the 2d defects (22). Acknowledgments
I am indebted to O. Andreev, M.N. Chernodub, A. Di Giacomo, M. D'Elia, A.S. Gorsky for enlightening discussions. References
[1] A. M. Polyakov, Phys. Lett. B72, 477 (1978); "Confinement and liberat'ion", [arXiv:hep-th/0407209].
325 [2] M.N. Chernodub and V.1. Zakharov, Phys. Rev.Lett. 98, 082002 (2007); "Magnetic strings as part of Yang-Mills plasma ", [arXiv:hepphj0702245]. [3] Ch. P. Korthals Altes, "Quasi-particle model in hot QCD", [arXiv:hepphj0406138]; Jinfeng Liao and E. Shuryak, Phys. Rev. C75, 054907 (2007), [arXiv:hep-phj0611131]. [4] M.N. Chernodub et al., "Topological defects and equation of state of gluon plasma", [arXiv:0710.2547]. [5] A. D'Alessandro and M. D'Elia, "Magnetic monopoles in the high temperature phase of Yang-Mills theories", [arXiv:0711.1266]. [6] A.M. Polyakov, "Gauge Fields and Strings", Harvard Academic Publishers, (1987) . [7J A.B. Zamolodchikov, Phys. Lett. B117, 87 (1982). [8] J. C. Myers and M.C. Ogilvie, "New phases of finite temperature gauge theory from an extended action", [arXiv:0710.0674J; Ph. de Forcrand, A.Kurkela, A. Vuorinen, "Center-Symmetric Effective Theory for HighTemperature SU(2) Yang-Mills Theory" [arXiv:0801.1566]. [9] A.M. Polyakov, Phys. Lett. B59, 82 (1975); M. E. Peskin, Annals Phys. 113, 122 (1978). [lOJ M.B. Halpern, Phys. Rev. D16, 1798 (1977); ibid D19, 517 (1979). [l1J V.1. Zakharov, Braz. J. Phys. 37, 165 (2007), [arXiv:hep-phj0612342J. [12J M.N. Chernodub, F.V. Gubarev, M.1. Polikarpov, V. I. Zakharov, Nucl.Phys. B600, 163 (2001), [arXiv:hep-thjOOl0265]. [13J S. Gukov and E. Witten, "Gauge Theory, Ramification, And The Geometric Langlands Program", [arXiv:hep-thj0612073J. [14] G. 't Hooft, Nucl. Phys. B190 , 455 (1981). [15J J. Greensite, Prog. Part. Nucl. Phys. 51, 1 (2003), [arXiv:heplatj0301023]. [16J V.1. Zakharov, AlP Conf. Proc. 756, 182 (2005), [arXiv:hepphj0501011]. [17] A. Di Giacomo, H. G. Dosch, V.1. Shevchenko, Yu.A. Simonov, Phys. Rept. 372, 319 (2002), [arXiv:hep-phj0007223]. [18J O. Aharony et al., Phys. Rept. 323,1832000, [arXiv:hep-thj9905111J. [19J O. Andreev, V.1. Zakharov, Phys. Rev, D74, 025023 (2006),[arXiv:hepphj0604204]; Phys. Lett. B645, 437 (2007), [arXiv:hep-phj0607026]; JHEP, 0704:100 (2007), [arXiv:hep-phj0611304]. [20J G. Burgio, PoS(LAT2007), 292 (2007), [arXiv:0710.0476J. [21] V.G. Bornyakov, V.K. Mitrjushkin, M. Muller-Preussker , Phys. Lett. B284, 99 (1992). [22J P. Petreczky, Nucl. Phys. A 785, 10 (2007), [arXiv:hep-Iatj0609040]. [23J A. Gorsky, V. Zakharov, "Magnetic strings in Lattice QCD as Nonabelian Vortices", [arXiv:0707.1284J.
LATTICE RESULTS ON GLUON AND GHOST PROPAGATORS IN LANDAU GAUGE I.L. Bogolubsky Joint Institute for Nuclear Research, 141980 Dubna, Russia
V.G. Bornyakov a Institute for High Energy Physics, 142281 Protvino, Russia and Institute of Theoretical and Experimental Physics, Moscow, Russia
G. Burgio Universitiit Tilbingen, Institut filr Theoretische Physik, 72076 Tilbingen, Germany
E.-M. Ilgenfritz, M. Miiller-Preussker Humboldt-Universitiit zu Berlin, Institut filr Physik, 12489 Berlin, Germany
V.K. Mitrjushkin Joint Institute for Nuclear Research, 141980 Dubna, Russia and Institute of Theoretical and Experimental Physics, Moscow, Russia Abstract. We present clear evidence of strong effects of Gribov copies in Landau gauge gluon and ghost propagators computed on the lattice at small momenta by employing a new approach to Landau gauge fixing and a more effective numerical algorithm. It is further shown that the new approach substantially decreases notorious finite-volume effects.
1
Introduction
The gauge-variant Green functions, in particular for the covariant Landau gauge, are important for various reasons. Their infrared asymptotics is crucial for gluon and quark confinement according to scenarios invented by Gribov [1] and Zwanziger [2] and by Kugo and Ojima [3]. They have proposed that the Landau gauge ghost propagator is infrared diverging while the gluon propagator is infrared vanishing. The interest in these propagators was stimulated in part by the progress achieved in solving Dyson-Schwinger equations (DSE) for these propagators (for a recent review see [4]). Recently it has been argued that a unique and exact power-like infrared asymptotic behavior of all Green functions can be derived without truncating the hierarchy of DSE [5]. This solution agrees completely with the scenarios of confinement mentioned above. The lattice approach is another powerful tool to compute these propagators in an ab initio fashion but not free of lattice artefacts. So far, there is no consensus between DSE and lattice results. For the gluon propagator, the ultimate decrease towards vanishing momentum has not yet been established in lattice computations. Lattice results for the ghost propagator qualitatively agree with the predicted diverging behavior but show a substantially smaller infrared exponent [6]. The lattice approach has its own limitations. The effects of the finite volume might be strong at the lowest lattice momenta. Moreover, gauge fixing is ae-mail: [email protected]
326
327 not unique resulting in the so-called Gribov problem. Previously it has been concluded that the gluon propagator does not show effects of Gribov copies beyond statistical noise, while the ghost propagator has been found to deviate by up to 10% depending on the quality of gauge fixing [7,8]. Recently anew, extended approach to Landau gauge fixing has been proposed [9]. In this contribution we present results obtained within this new method and using a more effective numerical algorithm for lattice gauge fixing, the simulated annealing (SA) algorithm. Results for the gluon propagator have been already discussed in [10], while results for the ghost propagator are presented here for the first time. 2
Computational details
Our computations have been performed for one lattice spacing corresponding to rather strong bare coupling, at f3 == 4/ g6 = 2.20, on lattices from 84 up to 324. The corresponding lattice scale a is fixed adopting ..j(ia = 0.469 [ll] with the string tension put equal to a = (440 Me V)2. Thus, our largest lattice size 32 4 corresponds to a volume (6.7 fm)4. In order to fix the Landau gauge for each lattice gauge field {U} generated by means of a Me procedure, the gauge functional
(1) is iteratively maximized with respect to a gauge transformation g(x) which is usually taken as a periodic field. In SU(N) gluodynamics the lattice action and the path integral measure are invariant under extended gauge transformations which are periodic modulo Z(N),
g(x + Lv) = z"g(x),
z"
E Z(N)
(2)
in all four directions. Any such gauge transformation is equivalent to a combination of a periodic gauge transformation and a flip Ux " ----* z" Ux " for a 3D hyperplane with fixed X". With respect to the flip transformation all gauge copies of one given field configuration can be split into N 4 flip sectors. The traditional gauge fixing procedure considers one flip sector as a separate gauge orbit. The new approach suggested in [9] combines all N 4 sectors into one gauge orbit. Note, that this approach is not applicable in a gauge theory with fundamental matter fields because the action is not invariant under transformation (2), while in the deconfinement phase of SU(N) pure gluodynamics it should be modified: only flips in space directions are left in the gauge orbit. In practice, few Gribov copies are generated for each sector and the best one over all sectors is chosen by employing an optimized simulating annealing algorithm in combination with finalizing overrelaxation.
328 3
Results
Thus, we are looking for the gauge copy with the highest value of the gauge functional among gauge copies belonging to the enlarged gauge orbit as defined above. It is immediately clear that this procedure allows to find higher local maxima of the gauge functional (1) than the traditional ('old') gauge fixing procedures employing purely periodic gauge transformations and the standard overrelaxation algorithm. Obviously the two prescriptions to fix the Landau gauge, the traditional one and the extended one, are not equivalent. Indeed, for some modest lattice volumes and for the lowest momenta it has been shown in Ref. [9] that they give rise to different results for the gluon as well as the ghost propagators. Comparing results for different lattice sizes we found that the results seem to converge to each other in the large volume limit. It is important that results obtained with the new prescription converge towards the infinite volume limit much faster. In Fig. 1 the gluon propagator D(p2) is Yセ@
••
......
8 7
N
>6 o --5 Q)
L = 1.7 fm 0 L = 2.5 fm L = 3.4 fm v L = 5.0 fm '" eL = 6.7 fm 0 " hyperon excitations. Shown are the dynamical quark masses JLi. the confinement energies Eo and the hyperon masses M (all in units of MeV).
the P-wave baryons can be obtained with a spin independent energy eigenvalues corresponding to the confinement plus Coulomb potentials. Moreover this comparative study gives a better insight into the quark model results where the constituent masses encode the QCD dynamics.
Acknowledgment This work was supported by RFBR grants 05-02-17869 and 06-02-17120. References [1] T. Burch et al., Phys, Rev. D 74, 014504 (2006) [2] H. G. Dosch, Phys. Lett. 190, 177 (1987), H. G. Dosch, Yu. A. Simonov, Phys. Lett. 202, 339 (1988) [3] 1. M. Narodetskii and M. A. Trusov, Phys. Atom. Nucl. 67, 762 (2004); Yad. Fiz. 67, 783 (2004) [4] A. Yu. Dubin, A. B. Kaidalov, and Yu. A. Simonov, Phys. Lett. B323, 41 (1994) ; B343, 310 (1995) [5] O. N. Driga, 1. M. Narodetskii, A. 1. Veselov, arXiv: hep-ph/0712.1479 [6] Yu. A. Simonov, Phys. Lett. B 515, 137 (2001) ; A. DiGiacomo and Yu. A. Simonov, Phys. Lett. B 595, 368 (2001)
THEORY OF QUARK-GLUON PLASMA AND PHASE TRANSITION E.V.Komarov a, Yu.A.Simonov b ITEP, Moscow Abstract.Nonperturbative picture of strong interacting quark-gluon plasma is given based on the systematic Field Correlator Method. Equation of state, phase transition in density-temperature plane is derived and compared to lattice data as well as subsequent thermodynamical quantities of QGP.
1
Introduction
The perturbative exploring of quark-gluon plasma (QGP) has some difficulties in describing the physics of QGP and phase transitions. However, it was realized 30 years ago that nonperturbative (np) vacuum fields are strong ( [1]) and later it was predicted ( [2]) and confirmed on the lattice ( [3]) that the magnetic part of gluon condensate does not decrease at T > Te and even grows as T4 at large T. Therefore it is natural to apply the np approach, the Field Correlator Method (FCM) ( [4]) to the problem of QGP and phase transitions, which was done in a series of papers ( [5]- [9]). As a result one obtains np equation of state (EoS) of QGP and the full picture of phase transition, including an unbiased prediction for the critical temperature Te(P,) for different number of flavors nt.
2
Nonperturbative EoS of QGP
We split the gluonic field AIL into the background field BIL and the (valence gluon) quantum field aIL: AIL = BIL + aIL both satisfying the periodic boundary conditions. The partition function averaged both in perturbative and np fields is
Z(V, T) = (Z(B
+ a))B,a
(1)
Exploring free energy F(T,p,) = -Tln(Z(B))B that contains perturbative and np interactions of quarks and gluons (which also includes creation and dissociation of bound states) we follow so-called Single Line Approximation (SLA). Namely, we assume that quark-gluon system for T > Te stays gauge invariant, as it was for T < Te , and neglect all perturbative interactions in the first approximation. Nevertheless in SLA already exist a strong interaction of gluons (and quarks) with np vacuum fields. This interaction consists of colorelectric (CE) and colormagnetic (CM) parts. The CE part in deconfinement phase creates np self-energy contribution for every quark and gluon embedded ae-mail: [email protected] be-mail: [email protected]
334
335
in corresponding Polyakov line. An important point is that Polyakov line is computed from the gauge invariant qij (gg) Wilson loop, which for np Df interaction splits into individual quark (gluon) contributions. As for CM part - its consideration is beyond the SLA, because as has been recently shown in paper ( [10]) strong CM fields are responsible for creation of bound states of white combinations of quarks and gluons. To proceed with FCM we apply the nonabelian Stokes theorem and the Gaussian approximation to compute the Polyakov line in terms of np field correlators Lfund = tr Pexp (i9 B 4 (z)dz 4 ) = c
It
J
J tr c
with
exp ( Mセ@
ISnISn daJ.L" (u)dO)'o.a (v)DJ.L"')..cr ) (2)
DJ.L"')..cr == g2 (FJ.L" (u)(u, v)F>.a(v)(V, u)) Df and DE arise from CE field strengths:
[E +DIE +U420D f] ッオセ@ +UiUk oDf oiP
1 Nc DOi,Ok = 6ik D
(3)
As a result the Polyakov loop can be expressed in terms of "potentials" VI and VD VI(T)+2VD) 9/4 (4) Lfund = exp ( 2T ,Ladj = (Lfund) , with Vl(T) == VI(oo,T), VD == VD(r*,T) ([5])
1 21
00
VI(r, T)
=
dv(l - vT)
00
VD(r, T)
=
dv(l - vT)
1T 、セ@
lT 、セ@
セdヲH@ (r -
jセR@ セIdeH@
+ v 2)
(5)
Je + v2 )
(6)
In what follows we use the Polyakov line fit ( [8,9]) Lfund
(x = セL@
T)
= exp (- HQNセZURt@
(7)
)
The free energy F(T) of quarks and gluons in SLA can be expressed as a sum over all Matsubara winding numbers n with coefficients Ljund and lセ、ェ@ for quarks and gluons respectively. For nonzero chemical potential one can keep L fund,adj independent of 1-", treating np fields as strong and unchanged by in the first approximation. The final formulas for pressure of qgp are ( [7,9])
I-"
I-"
p pq == セT@
SLA
= nQヲセ@
[(I-"-Yl.) " T + " (I-"+Yl.)] -T
(8)
336 12
l,...,
DB
dセ@
2 D.4
02
0 Qセ@ oセ@
2.5
100
3..5
°
=
300
400
500
600
Figure 2: Analytic (8), (10) and lattice ( [11]) curves for pressure of QGP with nf = 0,2+ 1,3 from ([9]).
Figure 1: Fit (7) of Polyakov line for nf = and nf = 2)(black curves) to the lattice data ( [11]).
where v
200
mq IT and
1
00
m1 + X at high energies can be described in terms of the corresponding kinematic characteristics of the constituent subprocess written in the symbolic form (x1Mt) + (X2M2) -> m1 + (x1M1 + X2M2 + m2) satisfying the condition
(1) The equation is the expression of locality of hadron interaction at a constituent level. Here Xl and X2 are fractions of the incoming momenta P1 and P2 of the colliding objects with the masses M1 and M 2. They determine the minimum energy, which is necessary for production of the secondary particle with the mass m1 and the four-momentum p. The parameter m2 is introduced to satisfy the internal additive conservation laws (for baryon number, isospin, strangeness, and so on). The quantity n is introduced to connect kinematic (X1,2) and structural (8 1,2) characteristics of the interaction. It is chosen in the form
(2) where m is the mass of nucleon and 81 and 82 are factors relating to the fractal dimensions of the colliding objects. The fractions Xl and X2 are determined to maximize the value of n(X1,X2), simultaneously fulfilling the condition (1)
(3) The fractions X1,2 cover the full phase space accessible at any energy. According to the self-similarity principle the scaling function '¢ (z) is constructed as the function depending on the single dimensionless variable z expressed via dimensionless combinations of Lorentz invariants. It is written in the form 7rS -1 d3 (T (4) '¢ (z) = - (dN/dTJ )(T,n . J E dP3 Here, Ed3 (T/dp 3 is the invariant cross section, s is the center-of-mass collision energy squared, (Tin is the inelastic cross section, J is the corresponding Jacobian. The factor J is the known function of the kinematic variables, the
357
momenta and masses of the colliding and produced particles. The function 'I/J(z) is normalized as follows
1a';)O 'I/J(z)dz =
1.
(5)
The relation allows us to interpret the function 'I/J(z) as a probability density to produce a particle with the corresponding value of the variable z. According to the fractality principle the variable z is constructed as a fractal measure z = zon- 1 for the corresponding inclusive process. It reveals the property zen) -. 00 at n- 1 - . 00. The divergent part n- 1 describes the resolution at which the collision of the constituents can be singled out of this process. The n(X1,X2) represents relative number of all initial configurations containing the constituents which carry fractions Xl and X2 of the incoming momenta.
3
QeD test of z-scaling
Here we analyze the new data obtained by the STAR and PHENIX Collaborations [3,4] on high-PT spectra of nO mesons produced in PP collisions at VB = 200 GeV. The results are compared with the NLO QCD calculations in PT and z presentations. Figure lea) shows nO meson PT-spectra obtained at ISR (see [2] and references therein) and RHIC energies [3,4]. The strong dependence of cross sections on collision energy was experimentally observed. The scaling function 'I/J(z) for the same data are presented in Figure 1 (b). The shape of the scaling function for RHIC data (*,6) is found to be in good agreement with 'I/J(z) for the ISR data shown by the dashed line. The asymptotical behavior of 'I/J(z) is described by the power law, 'I/J(z) rv z-i3. The value of the slope parameter f3 is independent of kinematical variables. QPGセM
10 • 10 1
10 10
BGセ@
'.,.
p-p
BセN@
セL@
11'0
_2
...';'....
10 -.
'M'
10'" . . 10 .... QPセ@
10 ., QPセ@ Qoセ@
10 -.. 10 _II 10 MNセBオlj@
s'IJ, GeV b.
* ...
200
" __ 90 G
"'.
--.NLセ@
PHENIX
200 STAR 30-62 ISR
\"'"
10
a)
...
10
I
b)
Figure 1: The PT (a) and z (b) presentations of experimental data on inclusive cross sections of rro mesons produced in pp collisions at the ISR and RHIC [3,4].
358
" ....-----------, ,,' , p+p",,,,O+X
"
..
10-'
::'"
..u 10-11
'>
10-
:g;
セ@
E 10'" • 10-'
). セァ@ [Zァセ@
セ@
17)1 1t 10· oセLZM@
"';,':-', BG[SPセZMU@ BG[Rセ@ BG[RセP@ p,.. GeV/e
"":"'0
b)
a) '0·...-----------, '0'
セ@
10
:u
1 10 "
'>
10'"
セN@
セZNA@ |セゥᄋN@ セZ@
10'''0
p+p ... .,..O+X
p+p ....nO+X
",1. aA' -(3 >.2 ) , ->. 0 _0>.3 (3 >.2 0
C
C°
0>.3 (1- e- iO )
(5)
0 o >. 3 (-1 + ei6 ) 0 0 0
°
),
where A2 is the matrix (1) with 8=0. Then the transformation following form:
V セ@
PRotPCP
(1 - セ@ [A2' All),
PRot
= e A2 ,
セVI@
V takes the
PCP =
e
Al
,
(0 1)
(7)
CThe other possibility to separate the real and the imaginary parts would be the following: A2
0 =).,
(
1
-1 _0).,2 cos
(8)
0 (3).
0).,2
cos (8) )
-(3).,
0
and Ai
=
io).,3 s in8
0 1
0
0 0
0 0
362
where the commutator is of the order 0(>,4). Thus, in this approximation the transformation, corresponding to the quark mixing with CP violation, is composed of the purely rotational part PRot, which is related to the rotation matrix (2) via the formulae (3), (4) and the CP violating part PCP
PRo'
セ@
exp
HセIL@
>. -a >.3
a),3
-(3 >.2 0 (3 >.2 0
)
,
PCP
GゥョRセI@ 01 O.
So, within the exact theory one can say that for real systems, the property (7) can not occur if CPT symmetry holds and CP is violated. This means that the relation (7) can only be considered as an approximation.
3
Model calculations
In this Section we discuss results of numerical calculations performed within the use of the symbolic and numeric package "Mathematica" for the model considered by Khalfin in [4,5], and by Nowakowski in [8] and then used in [11]. This model is formulated using the spectral language for the description of Ks,KL and KO, K, by introducing a hermitian Hamiltonian, H, with a continuous spectrum of decay products (for details see [1]). Assuming that CPT symmetry holds but CP symmetry is violated and using the experimentally obtained values of the parameters characterizing neutral kaon complex make it possible within this model to examine numerically the Khalfin's Theorem as well as other relations and conclusions obtained using this Theorem (for details see [8, lID. The results of numerical calculations of the modulus of the ratio セュ@ for some time interval are presented below in Fig. 1. Analyzing the results of these calculations one can find that for x E (0.01,10),
Ymax(X) - Ymin(X) ':::: 3.3 where, Ymax(X)
= Ir(t)lmax
and Ymin(X)
X
10- 16 ,
= Ir(t)lmin-
(10)
401
セ、wMiGゥ
··C.2:
..
4
10
Figure 1: Numerical examination of the Khalfin's Theorem. Here y(x)
= Ir(t)1 == 1セュ@
I, x = If .t,
and x E (0.01,10).
Similarly, using "Mathematica" and starting from the amplitudes Ajk(t) and using the formulae for hll (t), h22(t) and the condition All (t) = A22(t) one can compute the difference (h ll (t) - h22 (t) for the model considered. Results of such calculations for some time interval are presented below in Fig. 2. An expansion of scale in the left panel of Fig. 2 shows that continuous fluctuations, similar to those in the right panel of Fig. 2, appear.
2.01' 10.
11
QNYBPMKセ[RGSZU@
x
1. 9S .10. 13 1.97 '10. 13
-1.5'10. 16
1.96 '10"l) 1.95-10. 13
Figure 2: The real part (left) and the imaginary part (right) of (hll(t) - h22(t))
*' .
There is y(x) = 3{(h ll (t) - h22(t) and y(x) = u(/3,B)'
P ( /3 B) rr n"
= dW,ru = Frr (n,/3,B) dW,il
iJ>rr(/3,B)'
(2)
= dWr +dW,ru = Fu(n,/3,B) + Frr (n,/3,B) cos 2 B dWgl+dW,il
iJ>u(/3,B)+iJ>rr(/3,B)cos 2 B
Where dWqu, dWcl are the quantum and the classical angular distributions of SR respectively, B is the angle between the vector of the magnetic field and the direction of the radiation propagation. In equations (2) the following notations are used:
4+3q
4+q
iJ>u(/3, B) = 16(1 _ q)5/2' iJ>rr(/3, B) = 16(1 _ q)1/2 ' n
Fu,rr(n,/3,B) = LFu,rr(vjn,/3,B), v=l
8v 2 x[' 2
(x)
F ( /3 B) n n-v (/3) = (2n + 1); (1 + p)2' Frr v; n, , B = u V j n" 1- p
x
= v 1 + p'
Where [n,n-v(X), {セLョMカHクI@
P=
./
2vq
V1- 2n + l'
q
= /3 2 sin2 B,
4 2[2
0 セ@
v qp
()
X (in n-v + p)2
q セ@
,
(3)
/3 2 < l.
are the Laguerre function and its derivative [1].
429
The remarkable thing is the following: at each fixed n the functions Pa ,7r (n, (J, 8) depend on one variable q only, where q = /3 2 sin 2 8:
Pa ,7r(n,{J,8)
= pJ':)(q).
(4)
The function P(n, /3, 8) dos not possess this property. At each fixed n these functions are strongly depend on both /3 and 8 and satisfy the inequality following from (2):
min{pJn)(q), pJn)(q)} セ@ P(n,{J,8) セ@ max{pJn) (q), pJn)(q)}. The study of ーjセI@
(5)
(q) functions properties
It is easy to see that in the nonrelativistic limit the (2, 3) from formulas (2, 3) imply
/3 « 1 (i. e.
q
< (J2
«
1)
(n)( 2n [ 37q ] (n) 2n [ 35 q ] Pa q):::::: 2n + 1 1 - 4(2n + 1) , P7r (q):::::: 2n + 1 1 - 4(2n + 1) , (6) P(n, /3, Therefore at
8) : : 2n2: 1 [1 -
q 4(2n + 1)
(35 + 1 + :OS2 8) ].
/3 « 1 we have p(n) (q) < P(n a
-
(.I
, p,
8) < p(n) (q) < セ@ -
7r
-
2n + 1
< l.
(7)
The functions ーjセIHアL@ P(n,{J,8) decrease while q increases at fixed n. While n increases at fixed q these functions increase but stay lower than unity and at n -t 00 tend to unity. Replacing the summation on v by the corresponding integration in (3) and using well-known approximations [1] of Laguerre functions by McDonald's functions K 1/ 3(X), K 2/3(x) we could easily find the following expressions in the ultrarelativistic case:
2 3
Ho
m c = --. eli
It evidently follows from (5) that the ーjセI@ (q) are monotonically decreasing functions on J.L (therefore at fixed q monotonically increasing functions on n
430
and at fixed n monotonically decreasing functions on q) tending to zero at J.L -+ 00 follows from (8). At J.L < < 1 we have
p(n)( ) セ@ u
1_
320J.L
2l7rv'3 '
q
p(n)() セ@ 1- 256J.L • ,.. q 157rv'3
(9)
It is obvious that inequality (7) changes to the opposite one:
1> pJn)(q) セ@ P(n,(3,O) セ@ pJn) (q).
(10)
It is obvious from (3) that the functions Fu,,..(n, (3, 0) are finite at any values of q (including q = 1). Hence, at q -+ 1 the following asympthotics always take place: pJn)(q) セ@ Au(n)(l- q)5/2, pJn)(q) セ@ A,..(n)(l- q)7/2. (11) Here Au,,..(n) are some numbers depending on n. This guaranties that at 1 q < < 1 the inequalities (10) hold and ーjセ@ (q), P(n, (3, 0) tend to zero at q -+ 1. The obtained results prove the validity of the following inequalities 0< min{pJn) (q), pJn)(q)} :S P(n,(3,O) :S max{pJn) (q), pJn)(q)} < 1. (12) In conclusion on the figures below we present the graphs of these functions for different n. 1.
1.
0.8
0.8
P( q- 24!SF3 q')]
= 1+
- interference of the charge radiation and radiation of intrinsic magnetic moment,
f )JL =
[1+'" 1+QMBGHセK@ 2
9
2
9
385.J3 432'
J];:2
- magnetic moment radiation due to the Larmor precession
fTh
)J
= (1 + ,,' 7 + 1- ,{ 1 2
9
2
9
);2
'='
434 - magnetic moment radiation due to the Thomas precession,
=[_ 1+ セG@
jL-Th
(_! _
1 + 1- セG@
2
fl
3
35-13
2
3
216 r;
J];:2 ':>
- interference of the Larmor and Thomas radiation,
fa
= 1+r;r;' [ 2
I'
a(,
245-13
r; 3
72
,2J_!!",2] + 1-r;r;' (49+ 175-13 J!!..e 9 2 6 r; 9
- radiation due to anomalous magnetic moment of an electron:
g-2 l1a = 11- 110 = -2-110 where Po formulae
ア]SQPhイセョR@
=en / 2m oc is the Bohr magneton. Besides, everywhere in these
m oc
2
2 mocp
]セイ@
(2)
2H
is a quantum parameter well-known in the synchrotron radiation theory, and factors
=
r;,r;' ±1 correspond to the spin quantum numbers, magnetic field.
H*
is the Schwinger critical
3. Spin light in the classical theory of synchrotron radiation Here we will show that the purely classical theory can explain completely the origin of the spin light. The radiation of electrical charge, possessing also an intrinsic magnetic moment in the classical theory, is described by the Lienard- Wiechert potentials and Hertz tensor polarization potentials [17]
Aa
eva, QafJ ]⦅セョ。ヲjN@ c RP v P
=_!
RP v P
Corresponding tensor of electromagnetic field is calculated by the formula
HUV
]lNセ⦅a{Liャョv}A@
2
c
d'i
d
c2
d'i 2
Q[,IlU n n V] U'
Using then the standard technique of classical theory of radiation with equations of an electron motion and spin precession in the homogeneous magnetic field in the linear approximation by 11 one can find the spectral-angular distribution of radiation power in the form
435
2 2 3 n { cos e 2 12 dO. = 47r y4 f32 sin 2 eJ n + J n + Tセ@
2
eL
f.loOJ COS e '} eoc f3 sin e nJ n J n WSR
dwn
=
'
(3)
=
Here OJ eoH / mocy is the cyclotron frequency coincident at g 2 with the frequency of spin precession. This formula is a generalization of the Schott formula for spectral-angular distribution of synchrotron radiation with respect to radiation of intrinsic magnetic moment of an electron. It can be shown that this formula reproduces exactly all properties of spin light concerned with radiation at Larmor precession and described by the semi-classical theory (see also Ref. [8]). Here we will show this on the example of calculating of total radiation power in the most actual ultrarelativistic case when
f.loOJ _ f.lo _ 1 liOJ _ 1 H _ 1 @セ eoc - eop - 2 moc 2 - 2y H* - 3y2 . Towards that purpose one should sum up the expression in formula (3) over the spectrum and integrate it over the angles. As a result we find the same formulas for total synchrotron radiation power and its polarization components as in the semiclassical theory but without recoil effects, Thomas precession and anomalous magnetic moment of an electron
W = (1 Kセ@
)W
eL
Wa = XKVセ@ eL
(
W;L =
Hセ@
7
SR '
1 .;:)
+ セ@
セ@
WSR ,W1/" = XKVセ@ eL
(
1
1 ';:)
i
セ@
) WSR ' W;L = ( + セ@
WSR '
(4)
) WSR .
This result does not depend on sequence of foregoing operations. Thus, this radiation is non-polarized as one could expect from the origin of the spin light. The formula for spectral-angular distribution is eL
dW 27 2( 2)2{K213 2 +--2 x2 2 - - = - - 2 Y l+x K1I3 dxdy 167r 1+ X 2 f.lo y2 yx } + VMセ@ ( )112 K1I3K2/3 WSR ' eOp 1+x2 Integration over the spectrum in this expression gives the angular distribution of synchrotron radiation power with additional term for the spin light
436
{3 [7 ---;;;- = 32 (1 +
2 5X + X2
eL
dW
X2 y12
+
Y'2
(1
35
+ 16 セ@
]
X2}
(1 + X2 t 2
WSR '
If the expression (15) is integrated over the angles, one can find the spectral composition of this radiation eL
f
dW 9..[3 {co - - = - y K 5/3(X)d.x dy 81T y
KMセ@
2
3
f
co K
I/3(X)d.x
}
W SR '
y
The terms for the spin light in the last two formulas are equal to doubled components for linear polarization of radiation. Naturally, further integration in the last formulas over the angular parameter x or over the spectrum leads us to the formulae (4). This result can be shown by another method. According to the general theory of relativistic radiation of point like magnetic moment, the part of energy corresponding to the mixed synchrotron radiation emitted per unit proper time is determined by expression ([5],see also Ref. [18], formula (6.17»
ap 2 dpaJ = 2 eof.1o (d n w ⦅セカ。@ ( d-r 3 c4 d-r 2 p c2
dwp nJ'O'w __ 1 naPw w w p ). d-r CT c2 P p
Here nap is the dimensionless classical tensor of spin, pa is the four-dimensional momentum of radiation. Its zero component gives the power of mixed radiation
W eL
=.:.. dpo r d-r
Substitution of the corresponding solution of equation of motion, and averaging over period of charge motion and over the spin precession gives
W
eL
r JwSR'
z =(l+.!.;=n 3'='
where
n z = イセ@ . As to recoil effects and Thomas precession they can be completely
described by classical methods but with use of quantum laws of conservation.
4. Conclusion
Thus, we have shown that the classical and quantum theory of spin light are in agreement with each other at the first approximation by Plank's constant. A question is arising: is the correspondence principle fulfilled in higher-order approximation with respect to the Plank constant? According to the method described earlier the answer to this question is fairly evident: all depends on the possibility of neglecting of the quantum effects and other factors like the Thomas precession.
437
An extraordinary example is radiation of a neutron in a homogeneous magnetic field which arises exclusively due to the spin flip in the quantum theory. Relativistic quantum theory of neutron radiation was developed by the group of Russian scientists (I. M. Ternov, V. G. Bagrov and A. M. Hapaev) [21]. The classical theory of neutron radiation emitted at the spin precession, which was developed by V. A. Bordovitsyn with coauthors [17-20], turned out to be in full accordance with the quantum theory but differs by a constant coefficient equal to 4, which, as it turned out, is connected with specific properties of quantum transition with spin-flip ([8]). However such radiation in the classical theory does not exist in the common interpretation. Therefore the correspondence principle in this case is inapplicable. With regard to the synchrotron radiation of an electron the correspondence principle applied to radiation of the intrinsic magnetic moment works very well in the limit case p セ@ 00 and on assumption that the value of anomalous magnetic moment is large enough to neglect the Thomas precession. Note that in the mixed synchrotron radiation the terms which are proportional to Plank constant and contain the anomalous magnetic moment are in full accordance with the classical theory. Apparently, this is connected with the fact that the anomalous magnetic moment does not undergo Thomas precession (see [22]) . It is easy to show that the developed here classical theory gives the same terms 2
for radiation without spin-flip and proportional to h as are derived by the semiclassical theory for spin radiation caused by Larmor precession. Thus, we have in detail considered here the spin light identification problem when the spin radiation proceeds against the background of powerful synchrotron radiation, recoil effects, and other relativistic phenomena. In its pure form the spin light contributes to the synchrotron radiation power as a small correction 2
proportional to h • At the present time the problem of spin light radiation of the relativistic magnetic moment is particularly urgent in connection with the construction of ultrahigh energy accelerators. The procedure for experimental observation of spin dependence of synchrotron radiation power was proposed in Budker Institute of Nuclear Physics (Novosibisk), and this experiment itself was described in [23-25]]. In this experiment synchrotron radiation power proportional to h was for the first time observed to be dependent on the spin orientation of a free electron moving in a macroscopic magnetic field. Now it is possible to carry out more detailed investigation of spin light. Acknowledgments
We thank Prof. Yu. L. Pivovarov. for interesting discussion on these problems and Prof. V.Ya. Epp for his help in improving of the paper. This work was supported by RF President Grant no. SS 5103.2006.2, and by RFBR grant no. 06-02-16 719.
438 References
[1] V. Bargmann, L. Michel, V. L. Telegdi, Phys. Rev. Lett. 2 (1959) 435. [2] A A Schupp, R. V. Pidd, H. R. Crane, Phys. Rev. 121 (1961) 1. [3] V. A Bordovitsyn, I. M. Ternov, V. G. Bagrov, SOY. Phys. Usp. 165 (1995) 1083 (in Russian). [4] V. A Bordovistyn, V. S. Gushchina, I. M. Ternov, Nucl. Instr. Meth. A 359 (1995) 34. [5] VA Bordovitsyn, Izv. Vuz. Fiz. 40, N22 (1997) 40 (in Russian). [6) G. N. Kulipanov, A E. Bondar, V. A Bordovitsyn et aI., Nucl. Instr. Meth. A405 (1998)191. [7] I. M. Ternov, Introduction to Spin Physics of Relativistic Particles, MSU Press (1997) 240 (in Russian). [8] Synchrotron Radiation Theory and its Development. Ed.V.ABordovitsyn, World Scientific, Singapore, 1999. See also: Radiation Theory of Relativistic Particles, Fizmatlit, Moscow, 2002 (in Russian). [9] VA Bordovitsyn, V.Ya. Epp, Nucl. Instr. Meth. A 220 (1998) 405. V. A Bordovitsyn, [10] A Lobanov, A Studenikin, Phys. Lett. B 564 (2003) 27. [11] A E. Lobanov, Phys. Lett. B 619 (2005) 136. [12] G. J. Bhabha, G.C. Corben, Proc. Roy. Soc. 178 (1941) 273. [13] A Bialas, Acta Phys. Polon, 22 (1962) 349. [14] M. Koisrud, E. Leer, Phys. Norv. 17 (1967) 181. [15] J .Cohn, H.Wiebe, J.Math. Phys. 17 (1976) 1496. [16] J. D. Jackson, Rev. Mod. Phys. 48 (1976) 417I. [17] V. A Bordovitsyn et aI., Izv. Vuz, Fiz.21, N25 (1978) 12; N210 (1980) 33. [18] V. A Bordovitsyn, G. K. Razina, N. N. Byzov, Izv. Vuz, Fiz. 23, N210 (1980) 33. [19] V. A Bordovitsyn, R. Torres, Izv. Vuz., Fiz. 29 N25 (1986) 38. [20] V. A Bordovitsyn, V.S.Guschina, Izv. Vuz., Fiz. 37, N21 (1994) 53. [21] I. M Ternov, V.G.Bagrov, A M. Khapaev, Zh. Exp. Teor. Fiz.48 919650 921 (in Russian), SOY. Phys, JETP 21 (1965) 613. [22] VA Bordovitsyn, V.V.Telushkin, Izv. Vuz., Fiz. 49, N2 (2006). [23] V.N.Korchuganov, G.N.Kulipanov, M.N.Mezentsev, et aI., Preprint INP 7783, INP, Novosibirsk (1977) . [24] AE.Bondar, E.L.Saldin, Nucl. Instr. Meth.195 (1982) 577. [25] S.ABelomestnykh, AE.Bondar, M.N.Yegorychev, et al. Nukl. Instr. Meth., 227 (1984) 173.
SIMULATION THE NUCLEAR INTERACTION Timur F. Kamalov a Physics Department, Moscow State Open University, 107966 Moscow, Russia Abstmct. Refined are the known descriptions of particle behavior with the help of Lagrange function in non-inertial reference systems depends of coordinates and their multiple derivatives. This entails existing of circumstances when at closer distances gravitational effects can prove considerably stronger than in case of this situation being calculated with the help of Lagrange function in inertial reference systems depends of coordinates and their first derivatives. For example, this may be the case if the gravitational potential is described as a power series in sir where s is a constant correspondence for the nuclei scale.
1
Simulation in real reference frame
1.1
Particles in real reference frame
Classical physics usually considers the motion of bodies in inertial reference systems. This is a simplified and approximate description of the real pattern of the motion, as it is practically impossible to get an ideal inertial reference system. Actually in any particular reference system there always exist minor influences. Let us consider the precise description of the dynamics of the motion of bodies taking into account complex non-inertial nature of reference systems. For this end, let us consider a body in a non-inertial reference system, denoting the position of the body as r and time as t. Then, expanding into Taylor series the function r = ret), we get
_ r - ro
at 2
1.
1 ..
3
1 . (n)
4
+ vt + - 2 + ,at + ,at + ... + ,a 3. 4. n.
t
n
+ ...
(1)
Let us compare this expansion with the well-known kinematical equation for inertial reference systems of Newtonian physics relating the distance to the acceleration a,
rNewton
at 2
= ro + vt + T·
(2)
Denoting the hidden variables accounting for additional terms in non-inertial reference systems with respect to inertial ones as qr, we get 1 .
3
qr = 3! at
1 ..
4
1 . (n)
+ 4! at + ... + n! a
n
t
+ ...
(3)
Then
r
=
rNewton
ae-mail: [email protected]
439
+q
(4)
440
For inertial reference systems the Lagrangian L is the function of only the coordinates and their first derivatives, L = L(t, r, r) For non-inertial reference systems, the Lagrangian depends on the coordinates and their higher deriva. .....
·(n)
tives as well as of the first one, i.e. L = L(t, r, r, r, r, ... , r ) Applying the principle of least action, we get [1]
J ......
JL.) セ@
n dn 8L (5) -1) dt n (--:(;0 ) Jrdt = O. n=O 8 r Then, the Euler - Lagrange function for complex non-inertial reference systems takes on the form JS = J
·(n)
L(r, r, r, r, ... , r )dt
=
(6) Or
(7) Denoting
p = p(2)
aL p
Or'
= 。セL@
ar
=
=aL
a.(4)' r
aT
p(3)
=
p(5)
=
·(4)
p(4)
aL
·(20 > s, we have the equation for the gravitational potential c.p = gュセ。L@ where a = l. For the short distances r < < s, we have the equation for the gravitational potential (11). For particles described by the generalized Lagrange function at small distances, i.e. when the series diverges, there shall be much stronger gravitational forces acting than it is usually considered in calculations employing the Lagrange function. This model of short-range gravitational interaction allows one to compare nuclear and gravitational interactions at small distances. Acknowledgments
I thank Professor A. Studenikin and Doctor A. Grigoriev for providing me the possibility of fruitful discussions. Reference
[lJ M. V. Ostrogradskii, M'emoires de l'Academie Imp'eriale des Sciences de Saint-P'etersbourg v. 6, 385 (1850).
UNSTABLE LEPTONS AND (p, - e - 7)- UNIVERSALITY O.Kosmachev a Joint Institute for Nuclear Research, 141980, Moscow Region, Dubna, Russia Abstract. Main advantage and virtue of proposed method is a possibility to describe and enumerate all possible types of free equations for stable and unstable leptons in the frame work of homogeneous Lorentz group by means of unique approach.
1
Introduction
Free states are necessary for description of interactions. As it is known they play the role of initial and final states. Free states equations are unique way to introduce in theory quantum numbers identifying any leptons. Such quantum numbers characterize an equation structure. They will be called structural quantum numbers. The proposed method succeed from those fundamental requirements as Dirac equation [1]: invariance of the equations relative to homogeneous Lorentz group taking into account four connected components; formulation of the equations on the base of irreducible representations of the groups, determining every lepton equation; conservation of four-vector of probability current and positively defined fourth component of the current; spin value of the leptons is proposed equal to 1/2. One can show [2] that a totality of enumerated physical requirements are necessary and sufficient conditions (together with some group-theoretical requirements) for formulation of lepton wave equation out of Lagrange formalism. As it was shown formerly [2] Dirac equation is related with three different irreducible representations of homogeneous Lorentz group.It follows from the fact that Dirac ,-matrix group contains two subgroups d" b, and dual property of d'Y. In this case standard (proper, orthochronous) representation is realized on d, group, T-conjugate representation is realized on b, group, P-conjugate representation is realized on I, group, Corresponding algebras (six-dimensional Lie algebras of homogeneous Lorentz group) are characterized completely by their commutative relations (CR). They are of the form for d, group [ai, ak]
= Cikl2a!,
rbi, bk )
=
-cikI 2a !,
[ai, bk)
= cikl 2b l,
where Cikl is Levi-Cevita tensor, i, k, l = 1,2,3; ai, bi are infinitesimal operators of three-rotations and boosts respectively and al '" ,3,2, a2 '" ,I'Y3 a3 == a}a2 '" a2ala2"1 = all, bl '" ,}, b2 '" ,2, b3 '" Here following definitions are used [1)
,2,},
[i( 'J.tPJ.t)
+ me]'ll =
,3·
0,
'J.t'v
+ 'v'J.t
ue-mail: [email protected]
443
= 28J.tv,
p" V =
1,2,3,4.
444
Commutative relations on the base of b')':
[ar, a2l
=
{「セL@
=
「セャ@
2a3, 2a3,
キィ・イ[「セ@
[aI, 「セャ@ = 0, [aI, 「セャ@ = 2b3 [a2' b3l = R「セL@ [a3, 「セャ@ = R「セL@ '" -/'1'/'4, 「セ@ the base of f')'-group:
b3l = MR「セL@ = R「セL@
[a 3,「セ}@
{。セLSャ@
= -
{「セLS}@
(1)
b3 '" -/'3/'4· Commutative relations on
'" -/'2/'4,
[aI, a2l = 2a3' {「セL@ 「セャ@ = - 2a 3' [aI, 「セャ@ = 0, [al,b 2l = 2b3, {。セL@
[a3, all = 2a2, [a2,a3] = 2al, [b3, セャ@「 = 2a2, {「セLS}@ = 2al, [a3, b3l = 0, [a2' b2l = 0, [al,b 3l = MR「セL@ [a2' 「セャ@ = -2b3, [a3, 「セャ@ = MR「セL@
2a l,
[a3' all = R。セL@
[b3, 「セ}@ = = 2al, [a3' b3l = {。セL@ 「セャ@ = 0, [al,b 3l = -2b 2, {。セL@ 「セャ@ = -2b3, [a3' 「セ}@ = R「セN@
MR。セL@
0,
(2)
The last connected component c" was obtained with following commutative relations:
[aI, 。セャ@
=
2a3'
[b"I' b"] 2 -- 2a '3 , {。イL「セャ@
[aI, 「セ}@ {。RL「セ}@
[a'3' b"l I
= 0, = R「セ@ = MR「セL@
--
2b"2'
[a2, a3l = -2ar, {「セL@ 「セ}@ = -2ar, {。セL@
「セャ@
= 0, = MR「セL@
[aI, 「セャ@ [a'2' b"l I - - 2b" 3' [a3' 「セャ@ = 「セN@R
[a3' ad = 。セL@R [b"3' b"] I -- 2a'2'
[a 3, 「セャ@
= 0,
(3)
The last three types of CR (1),(2),(3) ap to lately [2] were not represented in physical literature. Now we have the complete and closed set of constituents for description of lepton wave equations. 2
Equations for stable leptons
The base of every lepton equation is a corresponding /,-matrix group. Each of the /,-matrix group are produced by four generators. Three of them anticommute and ensure Lorentz invariance of different kinds. The fourth generator is a necessary condition for the formation of wave equation. The distinct nonidentical equations are became by virtue of different combinations of the four subgroups d,),' b,),' c')" fT Structural content of the groups for every type of equation has the form. 1. Dirac equation -
D')'[IIl: d,)" b,),' fl'.
445
2. Equation for doublet massive neutrino -
D'Y[I): d'Y' C'Y' IT
3. Equation for quartet massless neutrino -
D'Y[I I I): d'Y' b'Y' C'Y' IT
4. Equation for massless T-singlet -
D'Y[IV]: bT
5. Equation for massless P-singlet -
D'Y[V): cT
Every equation has its own structure allowing to distinguish one equation from other. All equations have not physical substructures, therefore leptons are stable. Obtained method allows to calculate full number of the stable leptons in the framework of starting suppositions. 3
Extensions of the stable lepton groups
Is it possible to obtain additional lepton equations on the bas of previous suppositions? This problem is attained by introducing additional (fifth) generator for new group production. As it turned out there are exist three and only three such possibilities. Each of them is equivalent to introduction of additional quantum characteristics (quantum numbers). The extension of Dirac ,-matrix group (D'Y(IJ)) by means of anticommuting generator r5 such that rg = I leads to 6.1-grouP with structural invariant [4],[3J equal to In[6.1J = -1. The extension of Dirac ,-matrix group by means of anticommuting generator イセ@ such that イセR@ = -I leads to 6.3-grouP with structural invariant equal to In[6.3) = o. The extension of neutrino doublet group (D'Y(I)) by means of anticommuting generator イセ@ such that イセR@ = -I leads to 6.2-groUP with structural invariant equal to In[6.21 = 1. al-grOUP has the following defining relations r JLr v
+ r vr JL =
28JLv,
(/-L, v
= 1,2,3,4,5)
(4)
One can show on the bas of (4) that 6. 1 contains 3 and only 3 subgroups of 32-order. As a result we have following content
6.t{D'Y(IJ),
D'Y(IIJ),
D'Y(IV)}
(5)
Relation (4) together with structural invariant In[6. 11 = -1 identify 6. 1 in physical sense. a 3 -group is obtained under extension of Dirac group by similar defining relations rsrt + rtr s = 28st , (s,t = 1,2,3,4), (6) (s = l,2,3,4),rg =-1. rsr5 + r5rs = 0, The group content was changed in this way
6.3{D'Y(IJ),
D'Y(I),
D'Y(IIJ)},
(7)
446
This corresponds to structural invariant iョ{セSQ@ A 2 -group and it defining relations.
rS t + rtr s
rsr4 + r 4r s r ur5 + r5r u
=
2b s t,
= 0, = 0,
= O.
(s,t=1,2,3), (s = QLRSIイセ@ =-l. (u = QLRSTIイセ@ =-1.
(8)
The group content differs from two previous cases セRサdLHiI@
Structural invariant is equal to iョ{セRQ@ 4
D, (III) ,
D,(V)},
(9)
= 1.
Conclusion
All examined equations have its own mathematical structure. These structures are not repeated, therefore they may be used for theoretical identification of the particles in free states. The first five equations including Dirac one have not physical substructures. Objects without structure can not disintegrate spontaneously , therefore all they are stable. The last three equations (AI, A 2 , A 3 ) have internal structures allowing of physical interpretation. If we suppose that the mass of the new particles is more than sum of masses of its constituents, they become candidates for unstable leptons. It is evidentally that equations on the base of Al and A3 may be interpreted as the equations for the massive charged leptons such as M± and T±. Their structural distinctions are the base for solving of the (M - e - T)universality problem by means of interaction descriptions. It is possible to relate A 2 -group with massive unstable neutrino. References [1] P.Dirac, Proc.Roy. Soc. A vol.117, 610 (1928). [2J O.Kosmachev, Representations of the Lorentz Group and Classification of Stable Leptons (Preprint JINR, P2-2006-6) Dubna, 2006. [3J A.Gusev, O.Kosmachev, Structural Quantum Numbers and Nonstable Leptons (preprint JINR, P4-2006-188) Dubna, 2006. [4J J.S. Lomont Applications of finite groups, (Academic Press, New York, London) 51, 1959.
GENERALIZED DIRAC EQUATION DESCRIBING THE QUARK STRUCTURE OF NUCLEONS A.Rabinowitch Abstract. We consider a generalization of the Dirac equation to describe the quark structure and anomalous magnetic moments of nucleons. The suggested generalization contains two 3 by 3 matrices consisting of the quark charges and describes a wave function of a nucleon having 12 components. It is shown that the magnetic moments of nucleons determined via the generalized Dirac equation accord with their experimental values.
As is known, the Dirac equation for the relativistic electron cannot be applied without substantial modifications to describe nucleons, since it does not give their anomalous magnetic moments. That is why a generalization of the Dirac equation was proposed in which an additional term describing non-minimal interaction of nucleons with electromagnetic fields was introduced [1,2]. However, this well-accepted generalization has two serious disadvantages. Namely, it does not describe the quark structure of nucleons and the experimental values of the anomalous magnetic moments of protons and neutrons cannot be deduced from it. Because of these reasons we seek another equation for nucleons which could be free of the two disadvantages. For this purpose let us consider the following generalization of the Dirac equation to describe nucleons:
(1) where F is the column consisting of three bispinors \{1k, k = 1,2,3, a and b are 3 x 3 matrices characterizing the quark structure of nucleons, 1 is the unit 3 x 3 matrix, are the Dirac matrices, n = 0,1,2,3, An are potentials of an external electromagnetic field, ep is the proton's charge, m is the rest mass of a nucleon when
27r decay (15 min) 18.35 K.Urbanowski (Univ. of Zielona Gora) Khaljin's Theorem and neutral meson subsystem (20 min) 18.55 AAIi (DESY), ABorisov , M.Sidorova (MSU) Bilinear R-parity Violation in Rare Meson Decays (15 min) 19.10 O.Kosmachev (JINR) Nonstable leptons and (p-e-r)-universality (15 min) 26 August, SUN 9.00-19.00
Bus excursion to Sergiev Posad
466 27 August, MON 9.00 - 13.50 MORNING SESSION (Conference Hall) Chairman: ADelia Selva 9.00 D.Gorbunov (INR) Status o/UHECR (30 min) 9.30 H.Gemmeke (lnst. for Data Processing and Electronics, Research Center Karlsruhe) The Auger experiment (30 min) 10.00 H.Gemmeke (lnst. for Data Processing and Electronics, Research Center Karlsruhe) Radio detection o/ultra high energy cosmic rays (30 min) 10.30 V.Flaminio (Univ. of Pis a) Neutrino telescopes in the deep sea (30 min) 11.00 C.Volpe (lPN CNRS) Beta-beams (30 min) 11.30 - 11.55 Tea break Chairman: V.Flaminio 11.55 G.Landsberg (Brown Univ.) Search/or extra dimensions and black holes at colliders 12.25 _D.Polyakov (Center for Adv. Math. Sci. & American Univ. of Beirut) New discrete states in two-dimensional supergravity quantum systems bound by gravity (20 min) 12.45 M.Fil'chenkov, S.Kopylov, Yu.Laptev (Peoples' Friendship Univ. of Russia) Quantum systems bound by gravity (20 min) 13.05 R.Nevzorov, S.Hesselbach, D.l.Miller, G.Moortgat-Pick, M.Trusov (Univ. of Glasgow) Lightest neutralino in the MNSSM (20 min) 13.25 C.Heusch (Univ. of California, St.Cruz) High-energy e-e-, gamma-e-, gamma-gamma interactions (25 min) 13.50 - 15.00 Lunch 15.00 - 19.15 AFTERNOON SESSION (Conference Hall) Chairman: C.Heusch 15.00 A.Isaev (lINR) Algebraic approach to analytical evaluation 0/ Feynman diagrams 15.20 KStepanyantz (MSU) Application o/higher covariant derivative regularization to calculation 0/quantum corrections in N= 1 supersymmetric theories (20 min) 15.40 O.Kharianov, LFrolov, V.Zhukovsky (MSU) Bound state problems and radiative effects in extended electrodynamics with Lorentz violation (20 min) 16.00 ALobanov, AVenediktov (MSU) Triangle anomaly and radiatively-induced Lorentz and CPT violation in electrodynamics (15 min) 16.15 - 16.55 Tea break Chairman: ABorisov 16.55 S.Vernov (SlNP MSU) Construction o/exact solutions in two-fields models (20 min) 17.15 KSveshnikov, M.Ulybyshev (MSU) Nonperturbative quantum relativistic effects in the confinement mechanism/or particles in a deep potential well (15 min) 17.30 AMykhaylov, Yu.Mykhaylov (MSU) Linearized gravity in a stabilized brane world model in five-dimensional Brans-Dicke theory (15 min) 17.45I.Fialkovsky, V.Markov, Yu.Pis'mak (St. Petersburg State Univ.) Parity violating thin shells in the framework o/QED (15 min) 18.00 T.Kamalov (Moscow State Open Univ.) Simulation the nuclear interaction (15 min) 18.15 O.Olkhov (Semenov Inst. ofChem. Phys.) Unique geometrization o/material and electromagnetic wave fields (IS min) 18.30 Yu.Rybakov (Peoples' Friendship Univ. of Russia) Open and closed cosmic chiral strings in general relativity (15 min) 18.45 M.Georgieva (Offshore Tech. Development Pte Ltd, Singapore) The size 0/ a parton
467 19.00 S.Gladkov (Moscow State Regional Univ.) On nonlinear dispersion of electromagnetic spectrum (IS min) 28 August, TUE 9.00 - 14.00 MORNING SESSION (Conference Hall) Chairman: B.Spaan 9.00 A.Kaidalov (ITEP) Some puzzles in B-decays (25 min) 9.25 V.Zakharov (ITEP) Nonperturbative physics at short distances (25 min) 9.50 M.Polikarpov (ITEP) Low dimensional manyfolds in lattice QCD (25 min) 10.15 Yu.Simonov (lTEP) Dynamics ofQCD at nonzero T and density (20 min) 10.35 G.Lykasov, AN.Sissakian, AS.Sorin, V.D.Toneev (JINR) Thermal effects in heavy-ion collisions (20 min) 11.55 ABadalian (ITEP) Decay constants ofheavy-light mesons (15 min) 11.10 - 11.30 Tea break Chairman: AKaidalov 11.30 N.Mankoc (Univ. of Ljubljana) Properties offour families ofquarks and leptons within the approach unifying spins and charges (25 min) 11.55 ANesterenko (JINR) Adler function within the analytic approach to QCD (20 min) 12.15 I.Narodetskii (ITEP) P wave baryons within the Field Corre/ator Method in QCD (20') 12.35 ASidorov (JINR) Polarized parton densities and higher twist corrections in the light of the recent CLAS and COMPASS data (20 min) 12.55 ANefediev (ITEP) Chiral symmetry breaking and the Lorentz nature of confinement 13.10 M.Osipenko (SINP MSU & INFN) Experimental moments of the structure function F2 ofproton and neutron (15 min) 13.25 V.Braguta (IHEP) Double charm onium production at B-factories and charmonium distribution amplitudes (20 min) 13.45 V.Bomyakov (IHEP) Lattice results on gluon and ghost propagators in Landau gauge 14.00 -15.00
Lunch
15.00 - 19.20 AFTERNOON SESSION (Conference Hall) Chairman: G.Diambrini Palazzi 15.00 AKataev (INR), V.Kim (INP, Gatchina) Higgs-+bb decay and different QCD corrections (20 min ) 15.20 I.Bogolubsky, E.-M.Ilgenfritz, M.Muelier-Preussker, AStembeck (JINR) Gluon and Ghost propagators in SU(3) gluodynamics on large lattices (15 min) 15.35 M.Tokarev (JINR) QCD test ofz-scalingfor piO-mesonproduction (15 min) 15.50 ASafronov (SINP MSU) Analytic approach to constructing effective theory ofstrong interactions and its application to pion-nucleon scattering (IS min) 16.05 D.Ebert, ATyukov, V.Zhukovsky (MSU) Phase transitions in dense quark matter in a constant curvature gravitational field (15 min) 16.20 K.Zhukovskii (MSU) Quark mixing in the standard model and the space rotations (15 min) 16.35 O.Pavlovsky (MSU) Effective Lagrangians andfield theory on a lattice (15 min) 16.50-17.10
Tea break
Chairman: V.Zhukovsky
468 17.10 AShabad (Lebedev Physics Inst.) String-like electrostatic interaction in QED with infinite magnetic field (20 min) 17.30 V.Skvortsov (MIPT), N.Vogel (Univ. of Tech. Chemnitz) Nuclear reactions and accompanying physical phenomena in plasma oflaser-induced discharges (15 min) 17.45 E.Arbuzova (Intern. Univ. "Dubna"), G.Kravtsova (MSU), V.Rodionov (Russian State Geological Prospecting Univ.) Particles with low binding energy in the strong stationary magnetic field (15 min) 18.00 V.Bagrov (Tomsk State Univ.) New results of synchrotron radiation theory (20 min) 18.20 V.Telushkin, V.Bordovitsyn (Tomsk State Univ.) Coherent Spin Light (15 min) 18.35 V.Sharikhin (Moscow Power Engineering Inst.) Microdrops condensation ofsolar photons in strong magnetic field (15 min) 18.50 ARabinowitch (Moscow State Univ. ofInstrument Construction and Informatics) A new generalization ofDirac's equationfor nucleons (15 min) 19.05 V.Belov, E.Smimova (Moscow Inst. of Electronics and Math.) Semiclassical soliton type solution of the nonlocal Gross-Pitaevsky equation (15 min)
29 August, WED MORNING SESSION (Conference Hall) Round Table Discussion on "Dark Matter and Dark Energy: a Clue to Foundations of Nature" Chairman and convener: AStarobinsky 9.00 AGalper (MEPhI), P.Picozza (Univ. of Rome-II) Antimatter and dark matter research in space (30 min) 9.30 AStarobinsky (Landau Inst.) Dark energy: present observational status, scalar-tensor andf(R) models (30 min) 10.00 R.Bemabei (Univ. of Rome-II) Investigating the dark halo (30 min) 10.30 AMalinin (Univ. of Maryland) Dark matter searches with AMS-02 (30 min) Tea break 11.00 -11.30 11.30 V.Dokuchaev (INR) Anisotropy of dark matter annihilation in the Galaxy (20 min) 11.50 V.Berezinsky (LNGS), Yu.Eroshenko (INR) Remnants of dark matter clumps in the Galaxy (20 min) 12.10 - 13.00 Discussion and conclusion 13.00 -14.30 Lunch
9.00-13.00
SEVENTH INTERNATIONAL MEETING ON PROBLEMS OF INTELLIGENTSIA: "Rights and Responsibility of the Intelligentsia" 14.30 -14.40 Opening (Conference Hall) Chairman: AStudenikin 14.40 V.Trukhin (Dean of the Faculty of Physics, Moscow State University) 15.00 S.Filatov (Found. for Social, Economical and Intellectual Programs) Rights and Responsibility of the Intelligentsia (30 min) 15.30 I.Bleimaier (Princeton) The Conscience of the Intelligentsia (30 min) 16.00 Discussion and conclusion Closing ofthe 13th Lomonosov Conference on Elementary Particle Physics and the 7th International Meeting on Problems of Intelligentsia SPECIAL SESSION (40 0)
List of participants of the 13th Lomonosov Conference on Elementary Particle Physics and the 7th International Meeting on Problems of Intelligentsia Andreotti Erica Arbuzova Elena Astafurov Vladimir Badalian Alia Bagrov Vladislav Balev Spasimir Barabash Alexander Barsuk Sergey Belokurov Vladimir Bernabei Rita Bleimaier John Bogolubsky Igor
Univ. of Insubria Int.Univ. ofDubna Group REI ITEP Univ.ofTomsk JINR ITEP LAL,Orsay MSU DAMA Princeton JINR
Borisov Anatoly Borisov Gennady Bornyakov Vitaly Braguta Victor Bunichev Viacheslav Chauveau Jacques Celnikier Ludwik Chekelian Vladimir Cherepashchuk Anatoly Cuhadar Donszelmann Tulay Curatolo Maria Della Selva Angelo Djurcic Zelimir Di Micco Biagio Di Ruzza Benedetto Diambrini Palazzi Giordano Dokuchaev Vladislav Egorychev Victor Eroshenko Yury Esposito Bellisario Fernandez Juan Pablo Fialkovsky Ignat Filatov Sergey
MSU Lancaster Univ. IHEP IHEP SINP Univ. Paris-VINII Observatoire de Meudon MPI SAl Univ. of British Columbia
Fil'chenkov Michael Flaminio Vincenzo Foster Brian Fujikawa Brian
INFN Frascati Univ. ofNeaples Columbia Univ. Univ .Rome-III Univ. of Trieste & INFN Trieste Univ.ofRome-I INR ITEP INR INFN Frascati CIEMAT St. Petersburg State Univ. Found. for Social, Economical and Intellectual Programs Peoples' Friendship Univ. of Russia Univ.ofPisa Univ.ofOxford LBNL
469
[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected], [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] giordano.diarnbrini@ romal.infn.it [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]
[email protected] [email protected] [email protected] [email protected]
470 Galper Arkady Gavrin Vladimir Gavryuseva Elena Gemmeke Hartmut
Gladkov Serguey Gorbunov Dmitry GrafKay Grats Yuri Greenberg Oscar Grigoriev Alexander Gutierrez Gaston Heusch Clemens Isaev Alexey Kadyshevsky Vladimir Kaidalov Alexei Kajino Toshitaka Kamalov Timur Kataev Andrei Kharlanov Oleg Kosmachev Oleg Kourkoumelis Christine Krasnikov Nikolay Kuznetsov Alexander Landsberg Greg Lobanov Andrei Lukash Vladimir Lykasov Gennady Madigozhin Dmitry Malinin Alexander Mankoc Borstnik Nonna Matveev Victor Mikhailin Vitaly Mikhailov Yuri Mikheyev Stanislav Mikheeva Elena Minakata Hisakazu Molokanova Natalia Murchikova Elena Narodetskii Ilya Nefediev Alexey Nesterenko Alexander Nevzorov Roman Nikishov Anatoly
MEPhl INR Inst. of Astrophys. and Space Research, Arcetri Inst. for Data Processing and Electronics, Research Center Karlsruhe Moscow State Regional Univ. INR Univ.ofErlangen-Nuremberg MSU Univ.ofMaryland MSU FNAL Univ. of California, St.Cruz JINR JINR ITEP Univ.ofTokyo Moscow State Open Univ. INR MSU JINR Univ. of Athenth INR Yaroslavl State Univ. Brown Univ. MSU LPI JINR JINR Univ.ofMaryland Univ.ofLjubljana INR MSU SINP INR LPI Tokyo Metropolitan Univ. JINR MSU ITEP ITEP JINR Univ.ofSouthampton LPI
amgalper@mephLru [email protected] [email protected] [email protected]
[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] mikheyev@pcbail O.inr .ruhep.ru [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] nikishov@lpLru
471 Nones Claudia
Nozzoli Francesco Ochoa-Ricoux Juan Okun Lev Olkhov Oleg Osipenko Mikhail Panasyuk Mikhail Partridge Richard Pavlovsky Oleg Polikarpov Mikhail Polyakov Dimitri Potrebenikov Yury Pranko Alexander Purohit Milind Rabinowitch Alexander Ray Heather Rodionov Vasily Rybakov Yuri Safronov Arkady Sakashita Ken Savrin Vladimir Shabad Anatoly Shabalin Evgeny Sharikhin Valentin Shaibonov Bair Shirkov Dmitry Sidorov Alexander Sidorova Maria Siebel Martin Simonov Yuri Sissakian Alexey Skvortsov Vladimir Slavnov Andrey Smirnova Ekaterina Spaan Bernhard Spillantini Piero Starobinsky Alexei Starostin Alexander Stepanyantz Konstantin Studenikin Alexander Tavkhelidze Albert
Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse Univ.ofRome-II California Inst. of Technology ITEP Semenov Inst. of Chern. Phys. SINP, INFN SINP& MSU Brown Univ. MSU ITEP Center for Adv. Math. Sci., American Univ. of Beirut JINR FNAL Univ. of South Carolina Moscow State Univ. ofInstrument Construction and Informatics LANL Moscow State Geological Prospecting Acad.
Peoples' Friendship Univ. of Russia SINP KEK SINP, Kurchatov Inst. Lebedev Phys. Inst. ITEP Moscow Power Engineering Inst. JINR JINR JINR MSU CERN ITEP JINR MIPT, Univ. of Tech. Chemnitz Steklov Math. Inst & MSU Moscow Inst. ofElectr. & Math. Univ.ofDortmund INFN-Florence LITP ITEP MSU MSU INR
[email protected], [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] shabad@lpLru [email protected] [email protected] bairsh@yandex. [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] smimova_ [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] a\[email protected]
472
Urbanowski Krzysztof
Tomsk State Univ. JINR Faculty of Physics, MSU MSU MSU CERN, Univ.ofCalifornia Univ. of Zielona Gora
Vannucci Francois Venediktov Artur Vemov Sergey Volpe Cristina Zakharov Valentin Zhukovsky Konstantin Zhukovsky Vladimir Zhuridov Dmitri
Univ. Paris 7 MSU SINP IPN CNRS ITEP MSU MSU MSU
Telushkin Valeriy Tokarev Mikhail Tmkhin Vladimir Tyukov Alexander Ulybyshev Maxim Unel Gokhan
[email protected] [email protected] [email protected] alex_ [email protected] [email protected] [email protected] [email protected]. zgora.pl [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]
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