Photon-Hadron Jet Correlations in p+p and Au+Au Collisions at \sqrt{s_{NN}}=200 GeV

Photon-Hadron Jet Correlations in + and Au+Au Collisions at =200 GeV

A. Adare University of Colorado, Boulder, CO 80309, U.S.    S. Afanasiev Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    C. Aidala Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Department of Physics, University of Massachusetts, Amherst, MA 01003-9337, U.S.    N.N. Ajitanand Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    Y. Akiba RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    H. Al-Bataineh New Mexico State University, Las Cruces, NM 88003, U.S.    J. Alexander Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    A. Al-Jamel New Mexico State University, Las Cruces, NM 88003, U.S.    K. Aoki Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    L. Aphecetche SUBATECH (Ecole des Mines de Nantes, CNRS-IN2P3, Université de Nantes) BP 20722 - 44307, Nantes, France    R. Armendariz New Mexico State University, Las Cruces, NM 88003, U.S.    S.H. Aronson Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    J. Asai RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    E.T. Atomssa Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    R. Averbeck Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    T.C. Awes Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    B. Azmoun Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    V. Babintsev IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    M. Bai Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    G. Baksay Florida Institute of Technology, Melbourne, FL 32901, U.S.    L. Baksay Florida Institute of Technology, Melbourne, FL 32901, U.S.    A. Baldisseri Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    K.N. Barish University of California - Riverside, Riverside, CA 92521, U.S.    P.D. Barnes Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    B. Bassalleck University of New Mexico, Albuquerque, NM 87131, U.S.    A.T. Basye Abilene Christian University, Abilene, TX 79699, U.S.    S. Bathe University of California - Riverside, Riverside, CA 92521, U.S.    S. Batsouli Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    V. Baublis PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    F. Bauer University of California - Riverside, Riverside, CA 92521, U.S.    C. Baumann Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    A. Bazilevsky Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    S. Belikov Deceased Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Iowa State University, Ames, IA 50011, U.S.    R. Bennett Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    A. Berdnikov Saint Petersburg State Polytechnic University, St. Petersburg, Russia    Y. Berdnikov Saint Petersburg State Polytechnic University, St. Petersburg, Russia    A.A. Bickley University of Colorado, Boulder, CO 80309, U.S.    M.T. Bjorndal Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    J.G. Boissevain Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    H. Borel Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    K. Boyle Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    M.L. Brooks Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    D.S. Brown New Mexico State University, Las Cruces, NM 88003, U.S.    D. Bucher Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    H. Buesching Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    V. Bumazhnov IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    G. Bunce Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    J.M. Burward-Hoy Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    S. Butsyk Los Alamos National Laboratory, Los Alamos, NM 87545, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    C.M. Camacho Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    S. Campbell Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    J.-S. Chai KAERI, Cyclotron Application Laboratory, Seoul, Korea    B.S. Chang Yonsei University, IPAP, Seoul 120-749, Korea    W.C. Chang Institute of Physics, Academia Sinica, Taipei 11529, Taiwan    J.-L. Charvet Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    S. Chernichenko IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    J. Chiba KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan    C.Y. Chi Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    M. Chiu Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    I.J. Choi Yonsei University, IPAP, Seoul 120-749, Korea    R.K. Choudhury Bhabha Atomic Research Centre, Bombay 400 085, India    T. Chujo Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan Vanderbilt University, Nashville, TN 37235, U.S.    P. Chung Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    A. Churyn IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    V. Cianciolo Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    Z. Citron Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    C.R. Cleven Georgia State University, Atlanta, GA 30303, U.S.    Y. Cobigo Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    B.A. Cole Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    M.P. Comets IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France    P. Constantin Iowa State University, Ames, IA 50011, U.S. Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    M. Csanád ELTE, Eötvös Loránd University, H - 1117 Budapest, Pázmány P. s. 1/A, Hungary    T. Csörgő KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, POBox 49, Budapest, Hungary    T. Dahms Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    S. Dairaku Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    K. Das Florida State University, Tallahassee, FL 32306, U.S.    G. David Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M.B. Deaton Abilene Christian University, Abilene, TX 79699, U.S.    K. Dehmelt Florida Institute of Technology, Melbourne, FL 32901, U.S.    H. Delagrange SUBATECH (Ecole des Mines de Nantes, CNRS-IN2P3, Université de Nantes) BP 20722 - 44307, Nantes, France    A. Denisov IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    D. d’Enterria Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    A. Deshpande RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    E.J. Desmond Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    O. Dietzsch Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil    A. Dion Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    M. Donadelli Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil    J.L. Drachenberg Abilene Christian University, Abilene, TX 79699, U.S.    O. Drapier Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    A. Drees Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    K.A. Drees Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A.K. Dubey Weizmann Institute, Rehovot 76100, Israel    A. Durum IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    D. Dutta Bhabha Atomic Research Centre, Bombay 400 085, India    V. Dzhordzhadze University of California - Riverside, Riverside, CA 92521, U.S. University of Tennessee, Knoxville, TN 37996, U.S.    Y.V. Efremenko Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    J. Egdemir Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    F. Ellinghaus University of Colorado, Boulder, CO 80309, U.S.    W.S. Emam University of California - Riverside, Riverside, CA 92521, U.S.    T. Engelmore Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    A. Enokizono Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.    H. En’yo RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    B. Espagnon IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France    S. Esumi Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    K.O. Eyser University of California - Riverside, Riverside, CA 92521, U.S.    B. Fadem Muhlenberg College, Allentown, PA 18104-5586, U.S.    D.E. Fields University of New Mexico, Albuquerque, NM 87131, U.S. RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M. Finger, Jr. Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech Republic Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    M. Finger Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech Republic Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    F. Fleuret Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    S.L. Fokin Russian Research Center “Kurchatov Institute”, Moscow, Russia    B. Forestier LPC, Université Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, France    Z. Fraenkel Deceased Weizmann Institute, Rehovot 76100, Israel    J.E. Frantz Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    A. Franz Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A.D. Frawley Florida State University, Tallahassee, FL 32306, U.S.    K. Fujiwara RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    Y. Fukao Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    S.-Y. Fung University of California - Riverside, Riverside, CA 92521, U.S.    T. Fusayasu Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, Japan    S. Gadrat LPC, Université Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, France    I. Garishvili University of Tennessee, Knoxville, TN 37996, U.S.    F. Gastineau SUBATECH (Ecole des Mines de Nantes, CNRS-IN2P3, Université de Nantes) BP 20722 - 44307, Nantes, France    M. Germain SUBATECH (Ecole des Mines de Nantes, CNRS-IN2P3, Université de Nantes) BP 20722 - 44307, Nantes, France    A. Glenn University of Colorado, Boulder, CO 80309, U.S. University of Tennessee, Knoxville, TN 37996, U.S.    H. Gong Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    M. Gonin Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    J. Gosset Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    Y. Goto RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    R. Granier de Cassagnac Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    N. Grau Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Iowa State University, Ames, IA 50011, U.S.    S.V. Greene Vanderbilt University, Nashville, TN 37235, U.S.    M. Grosse Perdekamp University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S. RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    T. Gunji Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    H.-Å. Gustafsson Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    T. Hachiya Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    A. Hadj Henni SUBATECH (Ecole des Mines de Nantes, CNRS-IN2P3, Université de Nantes) BP 20722 - 44307, Nantes, France    C. Haegemann University of New Mexico, Albuquerque, NM 87131, U.S.    J.S. Haggerty Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M.N. Hagiwara Abilene Christian University, Abilene, TX 79699, U.S.    H. Hamagaki Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    R. Han Peking University, Beijing, People’s Republic of China    H. Harada Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    E.P. Hartouni Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.    K. Haruna Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    M. Harvey Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    E. Haslum Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    K. Hasuko RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    R. Hayano Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    M. Heffner Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.    T.K. Hemmick Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    T. Hester University of California - Riverside, Riverside, CA 92521, U.S.    J.M. Heuser RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    X. He Georgia State University, Atlanta, GA 30303, U.S.    H. Hiejima University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    J.C. Hill Iowa State University, Ames, IA 50011, U.S.    R. Hobbs University of New Mexico, Albuquerque, NM 87131, U.S.    M. Hohlmann Florida Institute of Technology, Melbourne, FL 32901, U.S.    M. Holmes Vanderbilt University, Nashville, TN 37235, U.S.    W. Holzmann Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    K. Homma Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    B. Hong Korea University, Seoul, 136-701, Korea    T. Horaguchi Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan    D. Hornback University of Tennessee, Knoxville, TN 37996, U.S.    S. Huang Vanderbilt University, Nashville, TN 37235, U.S.    M.G. Hur KAERI, Cyclotron Application Laboratory, Seoul, Korea    T. Ichihara RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    R. Ichimiya RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    Y. Ikeda Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    K. Imai Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    J. Imrek Debrecen University, H-4010 Debrecen, Egyetem tér 1, Hungary    M. Inaba Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    Y. Inoue Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    D. Isenhower Abilene Christian University, Abilene, TX 79699, U.S.    L. Isenhower Abilene Christian University, Abilene, TX 79699, U.S.    M. Ishihara RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    T. Isobe Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    M. Issah Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    A. Isupov Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    D. Ivanischev PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    B.V. Jacak jacak@skipper.physics.sunysb.edu Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    J. Jia Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    J. Jin Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    O. Jinnouchi RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    B.M. Johnson Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    K.S. Joo Myongji University, Yongin, Kyonggido 449-728, Korea    D. Jouan IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France    F. Kajihara Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    S. Kametani Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN Waseda University, Advanced Research Institute for Science and Engineering, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan    N. Kamihara RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan    J. Kamin Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    M. Kaneta RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    J.H. Kang Yonsei University, IPAP, Seoul 120-749, Korea    H. Kanou RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan    J. Kapustinsky Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    T. Kawagishi Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    D. Kawall Department of Physics, University of Massachusetts, Amherst, MA 01003-9337, U.S. RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A.V. Kazantsev Russian Research Center “Kurchatov Institute”, Moscow, Russia    S. Kelly University of Colorado, Boulder, CO 80309, U.S.    T. Kempel Iowa State University, Ames, IA 50011, U.S.    A. Khanzadeev PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    K.M. Kijima Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    J. Kikuchi Waseda University, Advanced Research Institute for Science and Engineering, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan    B.I. Kim Korea University, Seoul, 136-701, Korea    D.H. Kim Myongji University, Yongin, Kyonggido 449-728, Korea    D.J. Kim Yonsei University, IPAP, Seoul 120-749, Korea    E. Kim System Electronics Laboratory, Seoul National University, Seoul, Korea    S.H. Kim Yonsei University, IPAP, Seoul 120-749, Korea    Y.-S. Kim KAERI, Cyclotron Application Laboratory, Seoul, Korea    E. Kinney University of Colorado, Boulder, CO 80309, U.S.    K. Kiriluk University of Colorado, Boulder, CO 80309, U.S.    A. Kiss ELTE, Eötvös Loránd University, H - 1117 Budapest, Pázmány P. s. 1/A, Hungary    E. Kistenev Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A. Kiyomichi RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    J. Klay Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.    C. Klein-Boesing Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    L. Kochenda PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    V. Kochetkov IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    B. Komkov PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    M. Konno Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    J. Koster University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    D. Kotchetkov University of California - Riverside, Riverside, CA 92521, U.S.    A. Kozlov Weizmann Institute, Rehovot 76100, Israel    A. Král Czech Technical University, Zikova 4, 166 36 Prague 6, Czech Republic    A. Kravitz Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    P.J. Kroon Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    J. Kubart Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech Republic Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic    G.J. Kunde Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    N. Kurihara Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    K. Kurita Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    M. Kurosawa RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    M.J. Kweon Korea University, Seoul, 136-701, Korea    Y. Kwon University of Tennessee, Knoxville, TN 37996, U.S. Yonsei University, IPAP, Seoul 120-749, Korea    G.S. Kyle New Mexico State University, Las Cruces, NM 88003, U.S.    R. Lacey Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    Y.-S. Lai Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    Y.S. Lai Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    J.G. Lajoie Iowa State University, Ames, IA 50011, U.S.    D. Layton University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    A. Lebedev Iowa State University, Ames, IA 50011, U.S.    Y. Le Bornec IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France    S. Leckey Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    D.M. Lee Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    K.B. Lee Korea University, Seoul, 136-701, Korea    M.K. Lee Yonsei University, IPAP, Seoul 120-749, Korea    T. Lee System Electronics Laboratory, Seoul National University, Seoul, Korea    M.J. Leitch Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    M.A.L. Leite Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil    B. Lenzi Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil    P. Liebing RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    H. Lim System Electronics Laboratory, Seoul National University, Seoul, Korea    T. Liška Czech Technical University, Zikova 4, 166 36 Prague 6, Czech Republic    A. Litvinenko Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    H. Liu New Mexico State University, Las Cruces, NM 88003, U.S.    M.X. Liu Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    X. Li China Institute of Atomic Energy (CIAE), Beijing, People’s Republic of China    X.H. Li University of California - Riverside, Riverside, CA 92521, U.S.    B. Love Vanderbilt University, Nashville, TN 37235, U.S.    D. Lynch Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    C.F. Maguire Vanderbilt University, Nashville, TN 37235, U.S.    Y.I. Makdisi Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A. Malakhov Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    M.D. Malik University of New Mexico, Albuquerque, NM 87131, U.S.    V.I. Manko Russian Research Center “Kurchatov Institute”, Moscow, Russia    E. Mannel Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    Y. Mao Peking University, Beijing, People’s Republic of China RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    L. Mašek Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech Republic Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic    H. Masui Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    F. Matathias Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    M.C. McCain University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    M. McCumber Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    P.L. McGaughey Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    N. Means Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    B. Meredith University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    Y. Miake Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    P. Mikeš Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech Republic Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic    K. Miki Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    T.E. Miller Vanderbilt University, Nashville, TN 37235, U.S.    A. Milov Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    S. Mioduszewski Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    G.C. Mishra Georgia State University, Atlanta, GA 30303, U.S.    M. Mishra Department of Physics, Banaras Hindu University, Varanasi 221005, India    J.T. Mitchell Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M. Mitrovski Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    A.K. Mohanty Bhabha Atomic Research Centre, Bombay 400 085, India    Y. Morino Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    A. Morreale University of California - Riverside, Riverside, CA 92521, U.S.    D.P. Morrison Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    J.M. Moss Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    T.V. Moukhanova Russian Research Center “Kurchatov Institute”, Moscow, Russia    D. Mukhopadhyay Vanderbilt University, Nashville, TN 37235, U.S.    J. Murata Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    S. Nagamiya KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan    Y. Nagata Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    J.L. Nagle University of Colorado, Boulder, CO 80309, U.S.    M. Naglis Weizmann Institute, Rehovot 76100, Israel    M.I. Nagy ELTE, Eötvös Loránd University, H - 1117 Budapest, Pázmány P. s. 1/A, Hungary    I. Nakagawa RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    Y. Nakamiya Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    T. Nakamura Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    K. Nakano RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan    J. Newby Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.    M. Nguyen Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    T. Niita Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    B.E. Norman Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    R. Nouicer Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A.S. Nyanin Russian Research Center “Kurchatov Institute”, Moscow, Russia    J. Nystrand Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    E. O’Brien Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    S.X. Oda Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    C.A. Ogilvie Iowa State University, Ames, IA 50011, U.S.    H. Ohnishi RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    I.D. Ojha Vanderbilt University, Nashville, TN 37235, U.S.    H. Okada Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    K. Okada RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M. Oka Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    O.O. Omiwade Abilene Christian University, Abilene, TX 79699, U.S.    Y. Onuki RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    A. Oskarsson Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    I. Otterlund Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    M. Ouchida Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    K. Ozawa Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan    R. Pak Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    D. Pal Vanderbilt University, Nashville, TN 37235, U.S.    A.P.T. Palounek Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    V. Pantuev Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    V. Papavassiliou New Mexico State University, Las Cruces, NM 88003, U.S.    J. Park System Electronics Laboratory, Seoul National University, Seoul, Korea    W.J. Park Korea University, Seoul, 136-701, Korea    S.F. Pate New Mexico State University, Las Cruces, NM 88003, U.S.    H. Pei Iowa State University, Ames, IA 50011, U.S.    J.-C. Peng University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    H. Pereira Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    V. Peresedov Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    D.Yu. Peressounko Russian Research Center “Kurchatov Institute”, Moscow, Russia    C. Pinkenburg Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    R.P. Pisani Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M.L. Purschke Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A.K. Purwar Los Alamos National Laboratory, Los Alamos, NM 87545, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    H. Qu Georgia State University, Atlanta, GA 30303, U.S.    J. Rak Iowa State University, Ames, IA 50011, U.S. University of New Mexico, Albuquerque, NM 87131, U.S.    A. Rakotozafindrabe Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    I. Ravinovich Weizmann Institute, Rehovot 76100, Israel    K.F. Read Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S. University of Tennessee, Knoxville, TN 37996, U.S.    S. Rembeczki Florida Institute of Technology, Melbourne, FL 32901, U.S.    M. Reuter Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    K. Reygers Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    V. Riabov PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    Y. Riabov PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    D. Roach Vanderbilt University, Nashville, TN 37235, U.S.    G. Roche LPC, Université Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, France    S.D. Rolnick University of California - Riverside, Riverside, CA 92521, U.S.    A. Romana Deceased Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    M. Rosati Iowa State University, Ames, IA 50011, U.S.    S.S.E. Rosendahl Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    P. Rosnet LPC, Université Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, France    P. Rukoyatkin Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    P. Ružička Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic    V.L. Rykov RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    S.S. Ryu Yonsei University, IPAP, Seoul 120-749, Korea    B. Sahlmueller Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    N. Saito Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    T. Sakaguchi Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan Waseda University, Advanced Research Institute for Science and Engineering, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan    S. Sakai Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    K. Sakashita RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan    H. Sakata Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    V. Samsonov PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    H.D. Sato Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    S. Sato Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    T. Sato Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    S. Sawada KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan    K. Sedgwick University of California - Riverside, Riverside, CA 92521, U.S.    J. Seele University of Colorado, Boulder, CO 80309, U.S.    R. Seidl University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    A.Yu. Semenov Iowa State University, Ames, IA 50011, U.S.    V. Semenov IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    R. Seto University of California - Riverside, Riverside, CA 92521, U.S.    D. Sharma Weizmann Institute, Rehovot 76100, Israel    T.K. Shea Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    I. Shein IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    A. Shevel PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    T.-A. Shibata RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan    K. Shigaki Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    M. Shimomura Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    T. Shohjoh Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    K. Shoji Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    P. Shukla Bhabha Atomic Research Centre, Bombay 400 085, India    A. Sickles Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S. Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    C.L. Silva Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil    D. Silvermyr Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    C. Silvestre Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    K.S. Sim Korea University, Seoul, 136-701, Korea    B.K. Singh Department of Physics, Banaras Hindu University, Varanasi 221005, India    C.P. Singh Department of Physics, Banaras Hindu University, Varanasi 221005, India    V. Singh Department of Physics, Banaras Hindu University, Varanasi 221005, India    S. Skutnik Iowa State University, Ames, IA 50011, U.S.    M. Slunečka Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech Republic Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia    W.C. Smith Abilene Christian University, Abilene, TX 79699, U.S.    A. Soldatov IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    R.A. Soltz Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.    W.E. Sondheim Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    S.P. Sorensen University of Tennessee, Knoxville, TN 37996, U.S.    I.V. Sourikova Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    F. Staley Dapnia, CEA Saclay, F-91191, Gif-sur-Yvette, France    P.W. Stankus Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    E. Stenlund Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    M. Stepanov New Mexico State University, Las Cruces, NM 88003, U.S.    A. Ster KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, POBox 49, Budapest, Hungary    S.P. Stoll Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    T. Sugitate Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    C. Suire IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France    A. Sukhanov Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    J.P. Sullivan Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    J. Sziklai KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, POBox 49, Budapest, Hungary    T. Tabaru RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    S. Takagi Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    E.M. Takagui Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil    A. Taketani RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    R. Tanabe Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    K.H. Tanaka KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan    Y. Tanaka Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, Japan    K. Tanida RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M.J. Tannenbaum Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    A. Taranenko Chemistry Department, Stony Brook University, Stony Brook, SUNY, NY 11794-3400, U.S.    P. Tarján Debrecen University, H-4010 Debrecen, Egyetem tér 1, Hungary    H. Themann Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    T.L. Thomas University of New Mexico, Albuquerque, NM 87131, U.S.    M. Togawa Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    A. Toia Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    J. Tojo RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    L. Tomášek Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic    Y. Tomita Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan    H. Torii Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    R.S. Towell Abilene Christian University, Abilene, TX 79699, U.S.    V-N. Tram Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France    I. Tserruya Weizmann Institute, Rehovot 76100, Israel    Y. Tsuchimoto Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    S.K. Tuli Department of Physics, Banaras Hindu University, Varanasi 221005, India    H. Tydesjö Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden    N. Tyurin IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    C. Vale Iowa State University, Ames, IA 50011, U.S.    H. Valle Vanderbilt University, Nashville, TN 37235, U.S.    H.W. van Hecke Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.    A. Veicht University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    J. Velkovska Vanderbilt University, Nashville, TN 37235, U.S.    R. Vertesi Debrecen University, H-4010 Debrecen, Egyetem tér 1, Hungary    A.A. Vinogradov Russian Research Center “Kurchatov Institute”, Moscow, Russia    M. Virius Czech Technical University, Zikova 4, 166 36 Prague 6, Czech Republic    V. Vrba Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic    E. Vznuzdaev PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia    M. Wagner Kyoto University, Kyoto 606-8502, Japan RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN    D. Walker Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.    X.R. Wang New Mexico State University, Las Cruces, NM 88003, U.S.    Y. Watanabe RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    F. Wei Iowa State University, Ames, IA 50011, U.S.    J. Wessels Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    S.N. White Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    N. Willis IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France    D. Winter Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    C.L. Woody Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    M. Wysocki University of Colorado, Boulder, CO 80309, U.S.    W. Xie University of California - Riverside, Riverside, CA 92521, U.S. RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    Y.L. Yamaguchi Waseda University, Advanced Research Institute for Science and Engineering, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan    K. Yamaura Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan    R. Yang University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.    A. Yanovich IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia    Z. Yasin University of California - Riverside, Riverside, CA 92521, U.S.    J. Ying Georgia State University, Atlanta, GA 30303, U.S.    S. Yokkaichi RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, JAPAN RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.    G.R. Young Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    I. Younus University of New Mexico, Albuquerque, NM 87131, U.S.    I.E. Yushmanov Russian Research Center “Kurchatov Institute”, Moscow, Russia    W.A. Zajc Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.    O. Zaudtke Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany    C. Zhang Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S. Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.    S. Zhou China Institute of Atomic Energy (CIAE), Beijing, People’s Republic of China    J. Zimányi Deceased KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, POBox 49, Budapest, Hungary    L. Zolin Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia
July 16, 2019
Abstract

We report the observation at the Relativistic Heavy Ion Collider (RHIC) of suppression of back-to-back correlations in the direct photon+jet channel in Au+Au relative to + collisions. Two-particle correlations of direct photon triggers with associated hadrons are obtained by statistical subtraction of the decay photon-hadron (-) background. The initial momentum of the away-side parton is tightly constrained, because the parton-photon pair exactly balance in momentum at leading order in perturbative quantum chromodynamics (pQCD), making such correlations a powerful probe of the in-medium parton energy loss. The away-side nuclear suppression factor, , in central Au+Au collisions, is for hadrons of 3  5 in coincidence with photons of 5  15 GeV/c. The suppression is comparable to that observed for high- single hadrons and dihadrons. The direct photon associated yields in + collisions scale approximately with the momentum balance,    / , as expected for a measure of the away-side parton fragmentation function. We compare to Au+Au collisions for which the momentum balance dependence of the nuclear modification should be sensitive to the path-length dependence of parton energy loss.

pacs:
13.85.Qk, 13.20.Fc, 13.20.He, 25.75.Dw

PHENIX Collaboration

I Introduction

Experimental results from RHIC have established the formation of hot and dense matter of a fundamentally new nature in relativistic heavy-ion collisions at GeV Adcox et al. (2005). Energy loss in this dense nuclear matter by color-charged, hard (E GeV) partons, and the jets into which they fragment, is generally accepted to be the mechanism responsible for the suppression of the high- hadron yields observed in central A+A collisions Adare et al. (2008a); Muller and Nagle (2006). In the large multiplicity environment of heavy-ion collisions, two-particle correlations are often used to study jet modification and to infer properties of the medium. For example, high- azimuthal dihadron correlations demonstrate that the degree of dijet away-side suppression depends on the  of the “trigger” and “associated” hadrons. At moderate  ( GeV/c), the jet properties measured through two-particle correlations demonstrate novel features such as shape modifications which are thought to be a manifestation of the response of medium to the energy deposited by the attenuated parton Adare et al. (2008b).

Di-hadron measurements of dijet pairs provide an ambiguous measurement of the energy loss of the away-side parton. The trigger hadron is a product of parton fragmentation and therefore it is not possible to determine, event-by-event, whether the near-side parton has itself lost energy. Given the steeply falling jet spectrum, the sample of hard scatterings is biased towards configurations in which the parton loses little energy. In particular, it is believed that hadron measurements are subject to a “surface bias” in which the hard scatterings sampled are likely to occur at the periphery of the overlap zone Muller (2003); Renk (2008). The away-side parton then is more likely to traverse a maximal path-length through the medium. For a sufficiently opaque medium, the attenuation of the parton may be nearly total, in which case the sensitivity to the average path-length is reduced  Eskola et al. (2005). Back-to-back, high- hadron pairs may originate preferentially from configurations in which the outgoing parton trajectories are tangential to the surface of the overlap zone Loizides (2007). On the other hand, dihadron pairs may also originate from vertices deep in the collision zone if a parton has a finite probability to “punch-through” or pass through the medium without interaction Renk and Eskola (2007). Calculations of the relative importance of these two mechanisms depend both on the model of parton energy loss employed and the density profile of the medium Renk (2008); Zhang et al. (2008); Drees et al. (2005).

Direct photon-jet pairs offer two major advantages in studying energy loss as compared to dijets because of the nature of the photon. First, in contrast to partons, photons do not carry color charge and hence do not interact strongly when traversing the medium Adler et al. (2005a). The distribution of hard scattering vertices sampled by direct photon-triggered correlations is thus unbiased by the trigger condition. Suppression of the opposite jet is averaged over all path-lengths given by the distribution of hard scattering vertices. Second, at the Born level, direct photon production in + and A+A collisions is dominated by the QCD Compton scattering process, ++, and the photon momentum in the center-of-mass frame is exactly balanced by that of the recoil quark. Although higher order effects and other complications to this idealized picture such as Next-to-Leading Order (NLO) “fragmentation” photons or soft gluon radiation must be considered, the level of suppression can then be related directly to the energy loss of a parton of known initial momentum. In this way, the average path-length of the away-side parton may then be varied in a well controlled manner by selecting events of various momentum differences between the - pair.

For this reason, the +jet channel has long been considered the “golden channel” for studying parton energy loss Wang and Huang (1997); Wang et al. (1996). Neglecting the above mentioned complications, specifically effects like transverse momentum broadening (the effect) and parton-to-photon fragmentation, back-to-back - correlations in elementary collisions directly measure the fragmentation function of the recoil jet since . In the standard picture of energy loss, partons are likely to lose some fraction of their energy in the medium, but are likely to fragment outside the medium. Hence, the parton energy loss can be considered an effective modification to the fragmentation function. Such a picture may be tested using - correlations in nuclear collisions. Complementary baseline measurements in + collisions are used to test the theoretical description of correlations in vacuum and to constrain possible contributions from higher order processes. Comprehensive reviews of direct photon phenomenology and data from elementary collisions may be found in Owens (1987); Ferbel and Molzon (1984); Vogelsang and Whalley (1997).

Ii Detector Description and Particle Identification

The data were taken with the PHENIX detector Adcox et al. (2003a) using approximately 950 million Au+Au minimum bias events from the 2004 data set and 471 million photon-triggered events from the 2005 and 2006 + data sets corresponding to integrated luminosities of 3 (2005) and 10.7 (2006) pb. The Beam-Beam Counters (BBC) Allen et al. (2003), which are used to trigger the minimum bias data, select 92% of the total inelastic cross section. In Au+Au the BBC and Zero-Degree Calorimeters (ZDC) were used for offline minimum bias event selection and centrality determination. In + collisions a high energy photon trigger, defined by coincidence between the BBC and a high energy Electromagnetic Calorimeter (EMCal) tower hit, was utilized. This EMCal based trigger Adler et al. (2003a) had an efficiency of 90% for events with photons and  with energies in the range used in the analysis and within the detector’s geometric acceptance.

The PHENIX central arms, each covering units of pseudorapidity around midrapidity and in azimuth, contain charged-particle tracking chambers and electromagnetic calorimeters Adcox et al. (2003b). The EMCal Aphecetche et al. (2003) consists of two types of detectors, six sectors of lead-scintillator (PbSc) sampling calorimeters and two of lead-glass (PbGl) Čerenkov calorimeters measuring EM energy with intrinsic resolution and 0.8% respectively. The fine segmentation of the EMCal ( for PbSc and for PbGl) allows for the reconstruction of ’s and ’s in the decay channel out to  of 20 GeV/c. The details of direct photon,   and meson detection and reconstruction within PHENIX have been described previously Adler et al. (2005a, 2007a, 2007b). Photon candidates with very high purity ( 98% for energies GeV) are selected from EMCal clusters with the use of cluster shower shape and charged particle veto cuts. Two-photon  and candidates are selected from photon pairs with pair invariant mass in the appropriate  or mass range. Combinatorial background is reduced with cuts on energy asymmetry , described in detail below. Some fraction of  with  starting at 13 GeV/c (in the PbSc detector) will appear as a single merged cluster, but with anomalous shower shape, and thus are removed from the analysis. The and mesons in the  range from about 4 to 17 GeV/c and photons between 5 and 15 GeV/c are used in this analysis. For  between 13–15 GeV/c there is a % contribution of merged  cluster contamination, however this together with all sources of non-photon contamination are found to have a negligible impact on the two-particle correlation analysis of this report. Direct photons and their two-particle correlations are obtained by statistical subtraction of the estimated meson (mainly ) decay photon contribution from the inclusive photon and - samples.

Charged hadrons are detected with the PHENIX tracking system Adcox et al. (2003c) which employs a drift chamber in each arm spanning a radial distance of 2.0–2.4 m from the beam axis with a set of pixel pad chambers (PC1) directly behind them. The momentum resolution was determined to be where is measured in GeV/c. Secondary tracks from decays and conversions are suppressed by matching tracks to hits in a second pad chamber (PC3) at distance of m. Track projections to the EMCal plane are used to veto photon candidates resulting from charged hadrons that shower in the EMCal.

Iii Method

iii.1 Two-Particle Correlations

Two-particle correlations are constructed by measuring the yield of particle pairs as a function of the measured azimuthal angle between photon or parent meson triggers and charged hadron partners. The correlation function, , corrects for the limited acceptance of - or meson-hadron pairs by dividing the distribution in real events by the mixed event distribution . The correlation function is decomposed utilizing a two-source model of pair yields coming from two-particle jet correlations superimposed on a combinatorial background yield from an underlying event. The underlying event in Au+Au is known to have an azimuthal asymmetry of harmonic shape quantified in the elliptic flow parameter Adare et al. (2009); Adler et al. (2006a). This flow represents a harmonic modulation of the  distribution of this underlying event, such that the flow-subtracted jet correlation signal is encoded in the jet pair ratio function, , using the notation of Adare et al. (2008b), where is the average single-particle .

Two methods of determining the background level , known as Zero-Yield at Minimum (ZYAM) and Absolute Normalization (ABS) respectively were applied to the Au+Au data. Both methods are described in detail in previous PHENIX publications  Adare et al. (2008b), see also Adler et al. (2005b); Adare et al. (2008b); McCumber and Frantz (2006) (ABS) and  Adler et al. (2006b) (ZYAM). ZYAM assigns the level of zero jet yield and hence to the minimum point of the correlation function . The ABS method uses the mean multiplicity of trigger-associated pairs in mixed events and a correction for finite centrality resolution to determine . Where ZYAM statistical precision is reasonable, the direct -h extraction of the two methods agree to within much better than the total uncertainties, typically within %. The ABS method is chosen for the Au+Au results presented, as this method resulted in a more precise extraction of direct photon-jet pair yields at high trigger  where lack of statistics near severely impairs the ZYAM determination. In the comparatively low multiplicity + collisions, the underlying event originates from different physical mechanisms than in Au+Au and is known not to be well described by event-mixing. Instead the correlation functions are normalized by fitting to a double Gaussian + constant function, corresponding to the ZYAM method Adare et al. (2008b).

The results presented here are corrected for the associated charged hadron efficiency such that the quoted yields correspond to a detector with full azimuthal acceptance and coverage. No correction is applied for the acceptance of pairs. Final results are presented in terms of the yield of jet pairs per trigger, with the constant .

The magnitudes of elliptic flow were determined by measuring the distributions of inclusive photons, neutral pions, and charged hadrons as a function of the angle relative to the reaction plane, which was determined with the BBC’s as described in Adler et al. (2003b). The  values measured for this analysis are consistent with previous PHENIX analyses Adare et al. (2009); Adler et al. (2006a); Adare et al. (). At high- ( GeV/c) the measured   values used in the determination of the decay photon  are fit to a constant function in order to reduce the effects of large statistical fluctuations. The  independence of  of ’s is motivated by recent preliminary data  Miki (2008) and also by the observed  independence of the , since parton energy loss is expected to be the dominant mechanism for generation at high- Eskola et al. (2005). It is also consistent with the findings of Adare et al. () which is direct measurement of   for the same dataset and is being published concurrently with this measurement. Since, as discussed in that publication, the high- functional behavior for this dataset cannot be well-constrained, the level of uncertainty we assign to the constant fit assumption increases with .

Table 1 lists the values for the inclusive and  decay photons for all  ranges used, either the measurements, or for the highest  decay values from the constant fit value. For the fit values the fit errors are listed as statistical error, despite the inherent systematic correlation of the fit value across the  bins. The decay photon is derived from the measured   by the same mapping procedure applied to the yields, described below. It is assumed that the for other mesons which contribute decay photons (e.g. ) are the same as that of the  at high-. This assumption is well motivated for the  range considered ( 4.5 GeV/c) under the expectation that the source of the high  azimuthal asymmetry is jet quenching-induced suppression, already measured to be the same for a variety of mesons (  itself Adler et al. (2007b)) and by data measurements for other high   which confirm the expectation Huang (2008) for other hadrons.

Inclusive Decay
Centrality Stat. Sys. Stat. Sys.
5–7 0.053 0.009 0.011 0.084 0.009 0.004
7–9 0.047 0.022 0.015 0.069 0.018 0.003
0–20% 9–12 0.024 0.042 0.017 0.069 0.020 0.003
12–15 0.064 0.096 0.094 0.069 0.023 0.003
5–7 0.096 0.010 0.005 0.155 0.011 0.036
7–9 0.079 0.027 0.011 0.105 0.019 0.025
20–40% 9–12 0.025 0.050 0.049 0.105 0.020 0.025
12–15 0.287 0.128 0.104 0.105 0.023 0.024
5–7 0.143 0.023 0.035 0.136 0.022 0.010
7–9 0.146 0.064 0.026 0.126 0.039 0.008
40–60% 9–12 0.162 0.126 0.252 0.126 0.042 0.008
12–15 -0.603 0.308 0.191 0.126 0.046 0.008
Table 1: values used in the jet function extraction for inclusive and decay photons in Au+Au collisions.

iii.2 Direct -Hadron Correlation Subtraction

A direct photon is defined here to be any photon not from a decay process. Direct photons cannot be identified in Au+Au with reasonable purity on an event-by-event basis due to the large background of meson decay in the  range of the analysis and the inability to use isolation cuts in the high multiplicity Au+Au environment. Thus both direct and - pairs must be determined from the already mentioned statistical subtraction procedure, which is therefore consistently used in this report for both the + and Au+Au.

Single direct photons have previously been measured in PHENIX, for Au+Au  Adler et al. (2005a), and + Adler et al. (2007c). In these analyses, the estimated yield of decay photons is subtracted from a measured sample of inclusive photons resulting in the direct photon yield. These measurements serve as an input to the current analysis, as they fix the fraction of the photon triggers which are expected to be direct. This fraction is quantified by the fraction . The  values used in this analysis are extracted from previous PHENIX measurements, Isobe (2007a, b) by interpolating to obtain the  binning used in this analysis. These interpolated values together with the error estimations are tabulated in Table 2.

Centrality Stat. Sys.
5-7 1.77 0.09 0.06
7-9 2.45 0.09 0.18
0-20% 9-12 2.99 0.11 0.41
12-15 3.66 0.24 0.68
5-7 1.46 0.10 0.04
7-9 1.85 0.10 0.12
20-40% 9-12 2.30 0.12 0.28
12-15 2.35 0.20 0.44
5-7 1.30 0.09 0.05
7-9 1.52 0.07 0.13
40-60% 9-12 1.85 0.10 0.30
12-15 1.94 0.24 0.36
5-7 1.18 0.01 0.06
7-9 1.33 0.01 0.05
+ 9-12 1.53 0.03 0.05
12-15 1.79 0.09 0.07
Table 2: Extracted  values used as input to direct -h per-trigger yield subtraction (Equation 2). These values are interpolated from previous PHENIX measurements as described in the text.

The per-trigger yield of inclusive - pairs is simply the weighted average of the contributions from decay and direct photon triggers,

(1)

Having already determined , may then be obtained by simple manipulation of the above terms resulting in statistical subtraction involving only per-trigger yields as follows. The decay photon per-trigger yield is subtracted from that of inclusive photons according to:

(2)

The direct or direct -h pair yields do not, by definition, exclude photons from jet fragmentation or medium induced photon production.

iii.3 Extraction of Decay Photon Correlations

The decay photon associated yields are estimated from the measured -h and -h correlations through a calculation which determines the decay correlations statistically from a Monte Carlo (MC) based, pair-by-pair weighting procedure. In this procedure the decay -h pair yield is constructed by a weighted integral over all -h and -h pairs. In what follows, we will first describe the procedure schematically, describing the ingredients and how they are obtained. We then give a more exact description and associated formula representing exactly how the weighting was performed in the measurement. Schematically the procedure may be expressed as a convolution of several factors according to the following relation, wherein for simplicity we only consider photons from  decay, although the procedure is also applied to decay photons.

(3)

where and are the  and single photon efficiencies, respectively, and is the decay probability density, each of which is addressed in turn below.

Figure 1: The weight factors used to obtain decay correlations from parent meson correlations. Top:  reconstruction efficiency correction, 1/. Middle: Decay probability function, , for 5–7 GeV/c decay photons from  derived analytically (black line), using the detector acceptance and resolution smearing (red line) and including the single decay photon efficiency, from a GEANT simulation (blue points). Bottom: obtained by taking ratio of the blue points to red curve in the previous panel.

First, since the starting point is the uncorrected raw meson-h pair yield , a correction for the parent meson reconstruction efficiency, , is applied to the raw ’s as a function of  in order to account for the  daughter photons in the inclusive sample whose sisters lie outside the PHENIX acceptance or are otherwise undetected. Both efficiencies , and in Equation 3 are also evaluated as a function of the position in the calorimeter along the beam direction, however this dependence mostly cancels in the ratio and therefore is suppressed for clarity. is determined by dividing the raw number of ’s obtained in the same data sample by the PHENIX published  invariant yields  Adare et al. (2007); Adler et al. (2007b); Adare et al. (2008a) assuming no pseudorapidity dependence over the narrow PHENIX acceptance. The top panel in Fig. 1 illustrates, for the example of central Au+Au events, the  efficiency correction factor 1/. The correction rises at small  due to a -dependent pair energy asymmetry cut designed to reduce combinatorial 2 pairs reconstructed as real ’s. This cut, along with the effects of any remaining background, is described below. At large   1/ rises again due to losses from cluster merging.

Second, the effect of decay kinematics is evaluated by determining the probability density, , for the decay of a -independent distribution of ’s. represents the relative probability of a  of =, to decay into a photon of . For a perfect detector, this function is calculable analytically. A simple fast MC generator implements the PHENIX acceptance and uses Gaussian smearing functions to simulate detector resolution according to the known EMCal energy and position resolution. Occupancy effects give rise to an additional smearing of the  and invariant masses. This effect is included in the MC by tuning the resolution parameters to match the  peak widths observed in data. False reconstruction of ’s and ’s from combinatorial matches are either subtracted or assigned to the systematic uncertainties as discussed below.

Finally, we wish to estimate the decay photon contribution to the measured raw inclusive photon sample which differs from the true decay photon distribution by the single decay photon efficiency, . At intermediate , depends only on the photon momentum and is included already implicitly by the fast MC simulation described above to produce . Thus, it is useful to think of them as a single factor At high-, on the other hand, an efficiency loss is incurred by photons from ’s whose showers merge into a single cluster in the calorimeter and are rejected by the shower-shape cut. As a consequence, the fraction of photons that are direct is artificially enhanced in the sample of reconstructed photon clusters. The single decay photon efficiency depends on both the parent and daughter  and is evaluated in a GEANT simulation. In principle the convolution of both and , , could be extracted as one function from the GEANT simulation, but obtaining large enough MC statistics necessary to properly parameterize the above mentioned EMCal z position dependence of the corrections is only feasible with the fast MC. Thus only the efficiency loss by cluster merging for photons is taken from the GEANT. The bottom panel of Fig. 1 shows evaluated from the GEANT simulation .

Since we wish to construct per-trigger yields, the same procedure described in Equation 3 can be applied to find the estimated single decay photon trigger yield from the measured single ś, replacing with and with . The exact application of schematic Equation 3 then takes the form of a sum over all -h pairs and single ś found in the data. Each  or -h pair is given a weight which depends on  . Operationally we now split this weight into two parts: discussed above and a factor . The factor is simply the end result of the fast MC-GEANT combined calculation, the convolution of and , including , averaged over a chosen decay photon bin of the range . Thus in terms of the product then is given by

(4)

Functions are defined for the four photon  bins used in the analysis, [a,b] = [5,7], [7,9], [9,12] and [12,15] GeV/c. An example of for the 5-7 GeV/c bin is shown in Fig. 1. Procedurally, we construct as product of the fast MC curve shown in the middle panel and the linear fit discussed above to the bottom panel, . Although a decay of  , the lower limit of the decay  bin, is kinematically disallowed, is non-zero below this boundary when resolution effects are considered. For  , decreases as , slowly enough that ’s at values of  beyond the statistical reach of the data set contribute to the relevant decay photon  selections at a non-negligible rate. The  sample is truncated at GeV/c and extrapolated using power-law fits to the single and conditional  spectra to estimate a correction. In the latter case, each associated hadron  range is fit independently. The truncation avoids the high- region where cluster merging effects are dominant and the correction factor becomes large. Although the truncation corrections for the number of decay photons and decay - pairs are non-negligible, they mostly cancel in the per-trigger yield and are therefore typically , reaching a maximum value of 7% for only the     GeV/c bin.

With the weight functions the entire set of -hadron pairs and single  candidates (within a given range of , , defining each  bin) are then summed over, once for each decay photon  bin, and the per-trigger yield is constructed for each of these decay  bins as

(5)

In this form it is clear that the normalization of the functions and cancel out completely in the per-trigger yield, and therefore only their shapes versus are important. Hence in Fig. 1 the curves are shown with arbitrary units. Also, as Equation 5 implies, the angular deviation between the direction of a decay photon and its parent meson is ignored. The  opening angle of a decay photon and hadron pair is taken to be the same as the of the parent -h pairs. This approximation is tested in the fast MC and found to be extremely accurate since the distribution of angular deviation between a leading decay photon in a 2 decay and the parent mesons at these  momenta have an RMS around 0 of radians, and the smallest  bins considered in the analysis are typically 0.1 radians or larger.

iii.4  and Reconstruction

In + collisions is estimated using both reconstructed  and mesons in invariant mass windows of 120–160 and 530–580 , respectively. The total decay per-trigger yield is calculated from

(6)

where is the ratio of the total number of decay photons to the number of decay photons from . Based on the measurements of Adler et al. (2007b) and Adler et al. (2008), which together with the  account for of decay photons, the value of is determined to be in the high- region covered by this analysis, independent of collision system and centrality. Note that the per-trigger yields for and other heavier meson triggers (,,,…) are not measured and are taken to be equivalent to in Equation 6. This assumption was studied in PYTHIA and found to influence at the level of . In Au+Au collisions correlations using triggers are not directly measured, but rather estimated from the + measurement as discussed below.

Figure 2 shows the various components of the decay photon measurement in +. In + collisions the rate of combinatorial background photon pairs is reduced by only considering photons of   GeV/c resulting in background levels of 10% for which no correction was applied. The effect of such remaining pairs on was evaluated to be negligible ( 2%) compared to the size of other uncertainties on the final result using a detailed full PYTHIA test of the method which included  reconstruction with combinatorial photon pairs. On the other hand, reconstruction has a much smaller signal-to-background of 1.4–1.6, depending on the  selection, even in the low multiplicity + environment. In this case, the per-trigger yield of the combinatorial photon pairs is estimated from photon pairs with invariant mass in “sideband” ranges of 400–460 and 640–700 , beyond 3 of the peak. The sideband contribution is then subtracted using the signal-to-background ratio evaluated from gaussian + polynomial background fits to the invariant mass distributions according to . The yield is generated from the full meson to decay photon weighting function procedure (Equation 5). The subtraction procedure was also tested in PYTHIA and the extracted and input per-trigger yields were found to agree to within 10%.

Figure 2: (color online) Examples of parent and daughter per-trigger yields for the  and in + collisions for  selection 5 7 and 2 3 GeV/c. These correlation measurements are used to determine the total decay photon per-trigger yield as described in the text.

In Au+Au collisions the combinatorial rate for  reconstruction is substantially larger. Correspondingly, a  dependent cut on the pair energy asymmetry  Adler et al. (2007a), visible in Fig. 1 with the smallest allowed asymmetry at the lowest   values, is used to reduce this background. With such cuts the signal-to-background in central events varies from 5:1 at its lowest, increasing to about 15:1 for the highest  selection. The effect of the combinatorial background is studied through examination of a similar sideband subtraction analysis as in the + correlation extraction described, this time for -h, using invariant mass ranges just outside the  peak region. However no clear trend beyond non-negligible statistical limitations is observed, so no correction for the background is applied. Instead the maximum size of the effect (typically 7%) is included as source of systematic uncertainty on the decay yields and propagated to the final direct photon per-trigger yields.

In central Au+Au collisions the meson cannot be reconstructed with sufficient purity to measure its correlations. Instead, a scaling argument is employed. Motivated by the similar high- suppression pattern shown by and  in Au+Au  Adler et al. (2007b) and corresponding near equality of the + and Au+Au ratios, the ratio is measured in + and applied as a correction to the Au+Au . This is justified by the assumption that the jet fragmentation is primarily occurring outside the medium. We do not attribute any additional uncertainty to this scaling beyond the 10% sideband systematic and statistical uncertainties of the measurement in +. However, to give an idea of the possible impact of this assumption, the total systematic error on from all other sources would correspond to a variation of the Au+Au by 50%. Given the similarity of the high- suppression demonstrated by all light quark bound states measured thus far, this would correspond to a rather large change.

Iv Systematic Uncertainties

There are four main classes of systematic uncertainty in the Au+Au data: elliptic flow, normalization of the underlying event (ABS), , and the decay per-trigger yield estimate, the latter two of which are present in the + data as well. Table 3 lists the fractional contribution of each of these sources to the total systematic uncertainty on the direct photon per-trigger yields in the 20% most central Au+Au and + data. In the central Au+Au data the uncertainty at low is dominated by the and correlation function normalization (ABS method) estimation due to large multiplicity of hadrons. At higher , but low trigger , , the decay error dominates due to the two-photon combinatorial background for  reconstruction. Finally, at large and the backgrounds responsible for both of these sources of uncertainty decrease and the uncertainty on , which is relatively constant, dominates. In + collisions the decay photon background forms a much larger fraction of the total photon sample. In this case, the decay uncertainty arises from the MC decay photon mapping procedure, the sideband subtraction and the ratio in approximately equal parts. The yields associated with daughter photons are larger than for the meson parents because of feed-down from larger values of parent , and hence, jet .

The correction for single hadron efficiency varies as a function of collision system and centrality. These corrections are obtained by finding the ratio of raw yields of hadrons obtained without the trigger condition in the same analysis () with the same cuts as in the analysis, to the previous PHENIX published measurements of the corresponding charged hadron spectra. Adler et al. (2004, 2005c). As in previous PHENIX two-particle correlation measurements, Adler et al. (2006b); Adare et al. (2008b), this procedure has inherent uncertainties assigned as a -independent 10% uncertainty, on each system and/or centrality.

Au+Au, Centrality 0-20 % +
(GeV) (GeV) Decay v2 Norm. Decay
1-2 0.03 0.14 0.50 0.33 0.14 0.86
5-7 2-3 0.02 0.32 0.46 0.20 0.21 0.79
3-5 0.02 0.71 0.18 0.10 0.05 0.95
1-2 0.09 0.17 0.45 0.29 0.22 0.78
7-9 2-3 0.10 0.35 0.38 0.17 0.25 0.75
3-5 0.09 0.61 0.18 0.13 0.21 0.79
1-2 0.06 0.09 0.53 0.33 0.19 0.81
9-12 2-3 0.26 0.25 0.33 0.16 0.30 0.70
3-5 0.46 0.30 0.13 0.10 0.35 0.65
1-2 0.08 0.01 0.63 0.29 0.21 0.79
12-15 2-3 0.21 0.14 0.48 0.17 0.02 0.98
3-5 0.22 0.14 0.39 0.25 0.10 0.90
Table 3: Fractional contribution to the total systematic uncertainty for each of the main sources of uncertainty in + and 0-20% Au+Au collisions.

V Results

v.1 Direct -h Per-Trigger Yields

Figure 3: (color online) Examples of per-trigger yields used in the direct photon correlation analysis for the 5 7 and 3 5 GeV/c bin. Top (bottom) panel: Inclusive, decay and direct photon per-trigger yields in + (0–20% central Au+Au) collisions.

Figure 3 shows examples of direct photon per-trigger yields in + and central Au+Au collisions. Also shown are the per-trigger yields for inclusive and decay photon triggers which are the ingredients in the statistical subtraction method as expressed in Equation 2. A clear away-side correlation is observed ( ) for direct photons triggers in +. In Au+Au collisions the away-side correlation is suppressed for both decay and direct photon triggers. The near-side direct photon associated yields are small relative to that of decay photons, an expected signature of prompt photon production Ferbel and Molzon (1984).

Figure 4: (color online) Direct - per-trigger yields for the range radians vs. associated hadron . Four different direct  ranges (indicated on the figure) are shown in the most central 20% of Au+Au events and + events. The upper limits are for 90% confidence levels. A -independent uncertainty of 10% due to the charged hadron efficiency correction is suppressed from the plot.
Yield Stat Sys Total
(GeV) (GeV) Au+Au, Centrality 0–20%
1-2 0.23 6.26e-02 4.72e-02 4.62e-02 6.60e-02
5-7 2-3 0.41 2.68e-02 1.29e-02 5.68e-03 1.41e-02
3-5 0.62 4.82e-03 2.13e-03 1.96e-03 2.90e-03
1-2 0.17 3.71e-02 8.48e-02 5.59e-02 1.02e-01
7-9 2-3 0.3 3.45e-02 2.39e-02 8.46e-03 2.53e-02
3-5 0.46 9.63e-03 4.18e-03 1.96e-03 4.62e-03
1-2 0.13 1.28e-01 1.34e-01 6.84e-02 1.51e-01
9-12 2-3 0.23 3.94e-02 3.81e-02 1.01e-02 3.94e-02
3-5 0.36 -2.16e-03 6.29e-03 2.06e-03 6.62e-03
1-2 0.1 5.31e-01 2.53e-01 1.49e-01 2.94e-01
12-15 2-3 0.18 -6.13e-03 6.99e-02 1.80e-02 7.22e-02
3-5 0.28 3.25e-02 1.60e-02 2.52e-03 1.62e-02
+
1-2 0.24 1.44e-01 9.93e-03 3.42e-02 3.56e-02
5-7 2-3 0.43 4.22e-02 5.47e-03 1.20e-02 1.32e-02
3-5 0.66 1.55e-02 2.07e-03 3.26e-03 3.86e-03
1-2 0.18 1.73e-01 1.84e-02 2.88e-02 3.42e-02
7-9 2-3 0.31 6.24e-02 1.11e-02 1.15e-02 1.60e-02
3-5 0.48 2.26e-02 4.53e-03 3.75e-03 5.88e-03
1-2 0.14 2.59e-01 2.99e-02 2.50e-02 3.90e-02
9-12 2-3 0.24 7.01e-02 1.73e-02 1.00e-02 2.00e-02
3-5 0.38 1.94e-02 7.21e-03 3.77e-03 8.14e-03
1-2 0.11 1.20e-01 5.13e-02 7.22e-02 8.86e-02
12-15 2-3 0.19 1.04e-01 3.11e-02 2.02e-02 3.71e-02
3-5 0.3 4.26e-02 1.62e-02 1.13e-02 1.97e-02
Table 4: Direct - per-trigger yields in 20% most central Au+Au and in + collisions. An additional -independent uncertainty of 10% due to the charged hadron efficiency corrections is not shown.

The away-side yields, integrated over radians, are shown in Fig. 4 and Table 4 for + and Au+Au collisions. This range roughly corresponds to the “head region” as defined in Adare et al. (2008b) and is chosen primarily to minimize the influence of medium response which is thought to dominate the “shoulder” region further offset from = . Additionally, the acceptance and the signal itself are largest in this range so statistical precision is maximized. It should be noted that the width of the jet correlation is larger than this interval. We do not make a correction for this effect, since we are primarily concerned with the comparison of the yields from + and Au+Au collisions. It should be noted, however, that in addition to parton energy loss, any broadening of azimuthal correlations, whether by hot or cold nuclear matter effects, will contribute to a suppression in the yield in the head region. Due to statistical and systematic fluctuations, the subtraction of the decay-photon hadron pairs from the inclusive - sample can result in a negative yield. In this case 90% confidence-level upper limits are given. In the case that a positive yield is obtained, but the uncertainty is consistent with 0, the lower bound of the error bar is also replaced with an arrow. As noted in the figure caption, a 10% -independent uncertainty due to the charged hadron efficiency corrections is not shown.

v.2 Suppression Factor

Departure from the vacuum QCD processes is quantified by , the ratio of Au+Au to + per-trigger yields:

(7)

Figure 5 shows the  values for all direct photon and associated hadron bins for the most central 0–20% of collisions. The data points for which the subtraction resulted in a negative yield value (the 90% confidence level upper limits) are included with standard 1- uncertainties. For the range 5–12 GeV/c, a significant suppression is observed in the GeV/c bin in which the highest precision is obtained. At lower , where the background subtraction is largest, the data do not have the statistical precision to determine the degree to which the yields are suppressed. for direct photon triggers is consistent to that of charged hadron triggers Adare et al. (2008b) as shown in the top left panel in which results with similar ranges of are compared.

Figure 5: (color online) Ratio of the Au+Au to + yields shown in Fig. 4. An additional -independent uncertainty of 14% due to the charged hadron efficiency corrections is not shown.
Figure 6: (color online) () integrated over the range 5   15 GeV/c for associated hadrons of 3   5 GeV/c vs. centrality compared to single  high-  (integrated over   5 GeV/c) Adare et al. (2008a). An additional -independent uncertainty of 14% due to the charged hadron efficiency corrections is not shown.

Figure 6 shows the for the  = 3–5 GeV/c bin, integrated for all trigger  bins ( = 5–15 GeV/c) and for three centrality bins, 0–20%, 20–40%, and 40–60%. For the most central bin, the suppression of the away-side direct photon per-trigger yield is clearly observed, . Within large uncertainties we see that the -jet in this  range, dominated by moderate to high values of (), is consistent with the single particle as a function of centrality, consistent with a scenario in which the geometry of suppression plays an important role as would be expected from a sample dominated by surface emission.

Figure 6 also compares from a measurement of high- dihadron () correlations Adare et al. (2008b) to the -jet result for similar selections. The two results are remarkably similar in the most central bin. This may indicate that surface emission is dominant for both samples in this region. However it should be noted that the total uncertainties on either measurement are still quite large on a relative scale. As explained in the introduction, the two measurements should be subject to different geometrical effects. Disentangling such effects through precise comparisons of dihadron and - suppression should be pursued with future measurements with improved statistics.

v.3 Towards the Fragmentation Function

Using the distribution of charged hadrons opposite direct triggers, parton energy loss may be studied directly as a departure from the (vacuum) fragmentation function. In distinction to -h correlations, where the away-side distribution is only sensitive to the integral of the fragmentation function (the average multiplicity of the away-side jet) Adler et al. (2006c), the away-side distribution for direct -h correlations provides a measurement of the full fragmentation function of the jet from the away-side parton. To the extent that the transverse momentum of the away-side parton and the direct are equal and opposite, as in leading order pQCD, the fragmentation function of the jet from the away-parton should be given to a good approximation by the distribution,

(8)

where the transverse momentum of the trigger =  in the case of -h correlations. The reasons why the scaling variable is an approximation to, rather than exact measure of, the fragmentation variable of the away-side jet with momentum are: i) the away-side parton does not generally balance longitudinal momentum with the trigger , although it is restricted by the acceptance of the detector; ii) the transverse momenta of the and away parton do not exactly balance. The transverse momentum imbalance was discovered at the CERN-ISR using distributions Della Negra and others (CCHK) (1977) and originally attributed to an “intrinsic” transverse momentum of each of the initial colliding partons Feynman et al. (1977), but now understood to be due to “resummation” of soft-gluon effects Kulesza et al. (2003); Aurenche et al. (2006).

Figure 7: distributions from the direct photon associated yields in + (left) and 0–20% Au+Au (right) collisions.

The validity of the approximation can be tested by observing identical distributions for different values of trigger  ( scaling), in which case one would accept the distribution in -h correlations as the quark fragmentation function from the reaction without need of correction. We approximate by , the ratio of the mean associated  to mean trigger  for each  bin.111The reader is advised to carefully distinguish this variable from our previous notation used in Adler et al. (2006c) of , which is the fraction of jet momentum contained in the trigger particle. The for the four trigger bins are: 5.66, 7.75, 10.07, 13.07 GeV/c, close to the values obtained from a fit to the direct- invariant cross section of the form  Adler et al. (2007c).

Figure 8: (color online) for the 20 % most central Au+Au data compared to predictions from an energy loss calculation  Wang (). An additional -independent uncertainty of 14% due to the charged hadron efficiency corrections is not shown.

Figure 7 shows the distributions for + and Au+Au collisions. The + data (Fig. 7a) exhibit reasonable scaling so that the measured distribution should represent the away-side jet fragmentation function. A fit of this data to a simple exponential gives an acceptable with a value which is consistent with the quark fragmentation function, parameterized Adler et al. (2006c) as a simple exponential with for , and inconsistent with the gluon fragmentation function value of . It should, however, be recalled that the data do not cover the full extent of the away peak, only radians, and that possible variations of the widths of the peaks in both the + data and the Au+Au data with and have not been taken into account in the present analysis. Additionally a more detailed analysis, differential in trigger , is necessary to study trigger  dependent effects which can influence the fragmentation function fit values Adler et al. (2006c).

In central Au+Au collisions, the fragmentation function may be modified by the medium222See Equation 1 in Zhang et al. (2007), so that scaling should not hold except in two special cases: i) pure surface emission or punch-through where the away-side jets are not modified—the distribution will be suppressed, but will have the same shape as in + collisions; ii) constant fractional energy loss of the away jet—the scaling will be preserved in Au+Au collisions but with a steeper slope than in + collisions. The Au+Au data (Fig. 7b) are consistent with scaling with the same shape as the + data, a value of and excellent for the simple exponential fit. The point at lowest for Au+Au is 1.6 standard deviations above the fit, suggesting that improved statistics will permit the observation of any non-surface emission.

v.4 Model Comparison

Several authors have reported predictions for -jet in heavy ion collisions Qin et al. (2008); Wang (); Arleo (2006); Renk (2006). As a demonstration of the how such calculations can be compared to the data, the  values as a function of are compared to energy loss predictions Wang () in Fig. 8. The calculation uses effective fragmentation functions to parameterize the energy loss in terms of a parameter which is expected to be proportional to the initial gluon density Zhang et al. (2007). The model calculates the energy-loss of the leading parton, and neglects the contribution the gluon radiation and medium response which may dominate at low values of . The data is well reproduced by the model over the range of values of provided, 1.48–1.88 GeV/fm. This corresponds roughly to the range of allowed by comparison to the PHENIX   data of Adare et al. (2008c).

It should be noted that the calculation rejects fragmentation photons with an isolation cut. Such a procedure has not yet been demonstrated in central Au+Au data, although doing so would help to eliminate beyond-leading-order effects.

Vi Conclusions

We have presented the first direct -h measurements in Au+Au and + collisions at RHIC. A significant suppression of for the away-side charged hadron yield in the range GeV/c is observed for direct photon triggers in Au+Au as compared to +. Furthermore, the level of suppression is found to be consistent with the single particle suppression rate and the importance of energy-loss geometry, notably the expectation of surface emission in the kinematic range sampled. A possible indication that energy-loss geometry may also be important in dijet suppression is that - suppression is also observed to be quite similar to that of dihadron suppression in central events; however, the current precision of the data does not exclude substantial differences. In the + data scaling is observed, suggesting that the measured distribution (Fig. 7) is a statistically acceptable representation of the fragmentation function of the quark jet recoiling away from the direct photon. Improvement of the statistical and systematic precision of the measurements should allow further tests of vacuum fragmentation expectations in p+p collisions and insights into details of the medium modification of jet fragmentation in Au+Au.

Acknowledgements

We thank the staff of the Collider-Accelerator and Physics Departments at Brookhaven National Laboratory and the staff of the other PHENIX participating institutions for their vital contributions. We acknowledge support from the Office of Nuclear Physics in the Office of Science of the Department of Energy, the National Science Foundation, a sponsored research grant from Renaissance Technologies LLC, Abilene Christian University Research Council, Research Foundation of SUNY, and Dean of the College of Arts and Sciences, Vanderbilt University (U.S.A), Ministry of Education, Culture, Sports, Science, and Technology and the Japan Society for the Promotion of Science (Japan), Conselho Nacional de Desenvolvimento Científico e Tecnológico and Fundação de Amparo à Pesquisa do Estado de São Paulo (Brazil), Natural Science Foundation of China (People’s Republic of China), Ministry of Education, Youth and Sports (Czech Republic), Centre National de la Recherche Scientifique, Commissariat à l’Énergie Atomique, and Institut National de Physique Nucléaire et de Physique des Particules (France), Ministry of Industry, Science and Tekhnologies, Bundesministerium für Bildung und Forschung, Deutscher Akademischer Austausch Dienst, and Alexander von Humboldt Stiftung (Germany), Hungarian National Science Fund, OTKA (Hungary), Department of Atomic Energy (India), Israel Science Foundation (Israel), Korea Research Foundation and Korea Science and Engineering Foundation (Korea), Ministry of Education and Science, Rassia Academy of Sciences, Federal Agency of Atomic Energy (Russia), VR and the Wallenberg Foundation (Sweden), the U.S. Civilian Research and Development Foundation for the Independent States of the Former Soviet Union, the US-Hungarian Fulbight Foundation for Educational Exchange, and the US-Israel Binational Science Foundation.

References

  • Adcox et al. (2005) K. Adcox et al. (PHENIX), Nucl. Phys. A757, 184 (2005), eprint nucl-ex/0410003.
  • Adare et al. (2008a) A. Adare et al. (PHENIX), Phys. Rev. Lett. 101, 232301 (2008a), eprint 0801.4020.
  • Muller and Nagle (2006) B. Muller and J. L. Nagle, Ann. Rev. Nucl. Part. Sci. 56, 93 (2006), eprint nucl-th/0602029.
  • Adare et al. (2008b) A. Adare et al. (PHENIX), Phys. Rev. C 78, 014901 (2008b), eprint 0801.4545.
  • Muller (2003) B. Muller, Phys. Rev. C 67, 061901 (2003), eprint nucl-th/0208038.
  • Renk (2008) T. Renk, Phys. Rev. C 78, 014903 (2008), eprint 0804.1204.
  • Eskola et al. (2005) K. J. Eskola, H. Honkanen, C. A. Salgado, and U. A. Wiedemann, Nucl. Phys. A747, 511 (2005), eprint hep-ph/0406319.
  • Loizides (2007) C. Loizides, Eur. Phys. J. A49, 339 (2007).
  • Renk and Eskola (2007) T. Renk and K. Eskola, Phys. Rev. C 75, 054910 (2007).
  • Zhang et al. (2008) H.-z. Zhang, J. F. Owens, E. Wang, and X. N. Wang, J. Phys. G35, 104067 (2008), eprint 0804.2381.
  • Drees et al. (2005) A. Drees, H. Feng, and J. Jia, Phys. Rev. C 71, 034909 (2005), eprint nucl-th/0310044.
  • Adler et al. (2005a) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 94, 232301 (2005a), eprint nucl-ex/0503003.
  • Wang and Huang (1997) X.-N. Wang and Z. Huang, Phys. Rev. C 55, 3047 (1997), eprint hep-ph/9701227.
  • Wang et al. (1996) X.-N. Wang, Z. Huang, and I. Sarcevic, Phys. Rev. Lett. 77, 231 (1996), eprint hep-ph/9605213.
  • Owens (1987) J. F. Owens, Rev. Mod. Phys. 59, 465 (1987).
  • Ferbel and Molzon (1984) T. Ferbel and W. R. Molzon, Rev. Mod. Phys. 56, 181 (1984).
  • Vogelsang and Whalley (1997) W. Vogelsang and M. R. Whalley, J. Phys. G23, A1 (1997).
  • Adcox et al. (2003a) K. Adcox et al. (PHENIX), Nucl. Instrum. Meth. A499, 469 (2003a).
  • Allen et al. (2003) M. Allen et al. (PHENIX), Nucl. Instrum. Meth. A499, 549 (2003).
  • Adler et al. (2003a) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 91, 241803 (2003a), eprint hep-ex/0304038.
  • Adcox et al. (2003b) K. Adcox et al. (PHENIX), Nucl. Instrum. Meth. A499, 489 (2003b).
  • Aphecetche et al. (2003) L. Aphecetche et al. (PHENIX), Nucl. Instrum. Meth. A499, 521 (2003).
  • Adler et al. (2007a) S. S. Adler et al. (PHENIX), Phys. Rev. C 76, 034904 (2007a), eprint nucl-ex/0611007.
  • Adler et al. (2007b) S. S. Adler et al. (PHENIX), Phys. Rev. C 75, 024909 (2007b).
  • Adcox et al. (2003c) K. Adcox et al. (PHENIX), Nucl. Instrum. Meth. A499, 489 (2003c).
  • Adare et al. (2009) A. Adare et al. (2009), in preperation (PPG098).
  • Adler et al. (2006a) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 96, 032302 (2006a), eprint nucl-ex/0508019.
  • Adler et al. (2005b) S. S. Adler et al. (PHENIX), Phys. Rev. C 71, 051902 (2005b).
  • McCumber and Frantz (2006) M. McCumber and J. Frantz, Acta Phys. Hung. A27, 213 (2006), eprint nucl-ex/0511048.
  • Adler et al. (2006b) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 97, 052301 (2006b).
  • Adler et al. (2003b) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 91, 182301 (2003b), eprint nucl-ex/0305013.
  • (32) A. Adare et al. (PHENIX), to be published.
  • Miki (2008) K. Miki (PHENIX), J. Phys. G35, 104122 (2008).
  • Huang (2008) S. Huang (PHENIX), J. Phys. G35, 104105 (2008), eprint 0804.4864.
  • Adler et al. (2007c) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 98, 012002 (2007c), eprint hep-ex/0609031.
  • Isobe (2007a) T. Isobe, Nucl. Phys. A783, 569 (2007a), eprint nucl-ex/0609028.
  • Isobe (2007b) T. Isobe (PHENIX), J. Phys. G34, S1015 (2007b), eprint nucl-ex/0701040.
  • Adare et al. (2007) A. Adare et al. (PHENIX), Phys. Rev. D 76, 051106 (2007), eprint 0704.3599.
  • Adler et al. (2008) S. S. Adler et al. (PHENIX), Phys. Rev. C 77, 014905 (2008), eprint 0708.2416.
  • Adler et al. (2004) S. S. Adler et al. (PHENIX), Phys. Rev. C 69, 034910 (2004), eprint nucl-ex/0308006.
  • Adler et al. (2005c) S. S. Adler et al. (PHENIX), Phys. Rev. Lett. 95, 202001 (2005c), eprint hep-ex/0507073.
  • Adler et al. (2006c) S. S. Adler et al. (PHENIX), Phys. Rev. D 74, 072002 (2006c), eprint hep-ex/0605039.
  • Della Negra and others (CCHK) (1977) M. Della Negra and others (CCHK), Nucl. Phys. B127, 1 (1977).
  • Feynman et al. (1977) R. P. Feynman, R. D. Field, and G. C. Fox, Nucl. Phys. B128, 1 (1977).
  • Kulesza et al. (2003) A. Kulesza, G. Sterman, and W. Vogelsang, Nucl. Phys. A721, 591 (2003), eprint hep-ph/0302121.
  • Aurenche et al. (2006) P. Aurenche, M. Fontannaz, J.-P. Guillet, E. Pilon, and M. Werlen, Phys. Rev. D 73, 094007 (2006), eprint hep-ph/0602133.
  • Zhang et al. (2007) H. Zhang, J. F. Owens, E. Wang, and X.-N. Wang, Phys. Rev. Lett. 98, 212301 (2007), eprint nucl-th/0701045.
  • Qin et al. (2008) G. Y. Qin, J. Ruppert, C. Gale, S. Jeon, and G. D. Moore (2008), eprint 0809.2030.
  • (49) X.-N. Wang, private communication.
  • Arleo (2006) F. Arleo, JHEP 09, 015 (2006), eprint hep-ph/0601075.
  • Renk (2006) T. Renk, Phys. Rev. C 74, 034906 (2006), eprint hep-ph/0607166.
  • Adare et al. (2008c) A. Adare et al. (PHENIX), Phys. Rev. C 77, 064907 (2008c), eprint 0801.1665.
Comments 0
Request Comment
You are adding the first comment!
How to quickly get a good reply:
  • Give credit where it’s due by listing out the positive aspects of a paper before getting into which changes should be made.
  • Be specific in your critique, and provide supporting evidence with appropriate references to substantiate general statements.
  • Your comment should inspire ideas to flow and help the author improves the paper.

The better we are at sharing our knowledge with each other, the faster we move forward.
""
The feedback must be of minimum 40 characters and the title a minimum of 5 characters
   
Add comment
Cancel
Loading ...
242489
This is a comment super asjknd jkasnjk adsnkj
Upvote
Downvote
""
The feedback must be of minumum 40 characters
The feedback must be of minumum 40 characters
Submit
Cancel

You are asking your first question!
How to quickly get a good answer:
  • Keep your question short and to the point
  • Check for grammar or spelling errors.
  • Phrase it like a question
Test
Test description