PHENIX Collaboration

# Production of $\pi^{0}$ and $\eta$ mesons in Cu$+$Au collisions at
$\sqrt{s_{{}_{NN}}}$=200 GeV

C. Aidala  Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040,
USA  N.N. Ajitanand  Deceased  Chemistry Department, Stony Brook University,
SUNY, Stony Brook, New York 11794-3400, USA  Y. Akiba<EMAIL_ADDRESS>RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198,
Japan  RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  R. Akimoto  Center for Nuclear Study, Graduate School of
Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  J.
Alexander  Chemistry Department, Stony Brook University, SUNY, Stony Brook,
New York 11794-3400, USA  M. Alfred  Department of Physics and Astronomy,
Howard University, Washington, DC 20059, USA  K. Aoki  KEK, High Energy
Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan  RIKEN
Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
N. Apadula  Iowa State University, Ames, Iowa 50011, USA  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  H. Asano  Kyoto University, Kyoto 606-8502, Japan  RIKEN
Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
E.T. Atomssa  Department of Physics and Astronomy, Stony Brook University,
SUNY, Stony Brook, New York 11794-3800, USA  T.C. Awes  Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37831, USA  B. Azmoun  Physics Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  V. Babintsev
IHEP Protvino, State Research Center of Russian Federation, Institute for High
Energy Physics, Protvino, 142281, Russia  A. Bagoly  ELTE, Eötvös Loránd
University, H-1117 Budapest, Pázmány P. s. 1/A, Hungary  M. Bai  Collider-
Accelerator Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  X. Bai  Science and Technology on Nuclear Data Laboratory,
China Institute of Atomic Energy, Beijing 102413, People’s Republic of China
B. Bannier  Department of Physics and Astronomy, Stony Brook University, SUNY,
Stony Brook, New York 11794-3800, USA  K.N. Barish  University of California-
Riverside, Riverside, California 92521, USA  S. Bathe  Baruch College, City
University of New York, New York, New York, 10010 USA  RIKEN BNL Research
Center, Brookhaven National Laboratory, Upton, New York 11973-5000, USA  V.
Baublis  PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad
region, 188300, Russia  C. Baumann  Physics Department, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  S. Baumgart  RIKEN Nishina Center
for Accelerator-Based Science, Wako, Saitama 351-0198, Japan  A. Bazilevsky
Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  M. Beaumier  University of California-Riverside, Riverside,
California 92521, USA  R. Belmont  University of Colorado, Boulder, Colorado
80309, USA  Vanderbilt University, Nashville, Tennessee 37235, USA  A.
Berdnikov  Saint Petersburg State Polytechnic University, St. Petersburg,
195251 Russia  Y. Berdnikov  Saint Petersburg State Polytechnic University,
St. Petersburg, 195251 Russia  D. Black  University of California-Riverside,
Riverside, California 92521, USA  D.S. Blau  National Research Center
“Kurchatov Institute”, Moscow, 123098 Russia  National Research Nuclear
University, MEPhI, Moscow Engineering Physics Institute, Moscow, 115409,
Russia  M. Boer  Los Alamos National Laboratory, Los Alamos, New Mexico 87545,
USA  J.S. Bok  New Mexico State University, Las Cruces, New Mexico 88003, USA
K. Boyle  RIKEN BNL Research Center, Brookhaven National Laboratory, Upton,
New York 11973-5000, USA  M.L. Brooks  Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, USA  J. Bryslawskyj  Baruch College, City University
of New York, New York, New York, 10010 USA  University of California-
Riverside, Riverside, California 92521, USA  H. Buesching  Physics Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  V. Bumazhnov
IHEP Protvino, State Research Center of Russian Federation, Institute for High
Energy Physics, Protvino, 142281, Russia  S. Butsyk  University of New Mexico,
Albuquerque, New Mexico 87131, USA  S. Campbell  Columbia University, New
York, New York 10027 and Nevis Laboratories, Irvington, New York 10533, USA
Iowa State University, Ames, Iowa 50011, USA  V. Canoa Roman  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  C.-H. Chen  RIKEN BNL Research Center, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  C.Y. Chi  Columbia University,
New York, New York 10027 and Nevis Laboratories, Irvington, New York 10533,
USA  M. Chiu  Physics Department, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  I.J. Choi  University of Illinois at Urbana-Champaign,
Urbana, Illinois 61801, USA  J.B. Choi  Deceased  Chonbuk National University,
Jeonju, 561-756, Korea  S. Choi  Department of Physics and Astronomy, Seoul
National University, Seoul 151-742, Korea  P. Christiansen  Department of
Physics, Lund University, Box 118, SE-221 00 Lund, Sweden  T. Chujo  Tomonaga
Center for the History of the Universe, University of Tsukuba, Tsukuba,
Ibaraki 305, Japan  V. Cianciolo  Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, USA  B.A. Cole  Columbia University, New York, New York 10027
and Nevis Laboratories, Irvington, New York 10533, USA  M. Connors  Georgia
State University, Atlanta, Georgia 30303, USA  RIKEN BNL Research Center,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  N. Cronin
Muhlenberg College, Allentown, Pennsylvania 18104-5586, USA  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  N. Crossette  Muhlenberg College, Allentown, Pennsylvania
18104-5586, USA  M. Csanád  ELTE, Eötvös Loránd University, H-1117 Budapest,
Pázmány P. s. 1/A, Hungary  T. Csörgő  Eszterházy Károly University, Károly
Róbert Campus, H-3200 Gyöngyös, Mátrai út 36, Hungary  Institute for Particle
and Nuclear Physics, Wigner Research Centre for Physics, Hungarian Academy of
Sciences (Wigner RCP, RMKI) H-1525 Budapest 114, POBox 49, Budapest, Hungary
T.W. Danley  Department of Physics and Astronomy, Ohio University, Athens,
Ohio 45701, USA  A. Datta  University of New Mexico, Albuquerque, New Mexico
87131, USA  M.S. Daugherity  Abilene Christian University, Abilene, Texas
79699, USA  G. David  Physics Department, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  Department of Physics and Astronomy, Stony
Brook University, SUNY, Stony Brook, New York 11794-3800, USA  K. DeBlasio
University of New Mexico, Albuquerque, New Mexico 87131, USA  K. Dehmelt
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony
Brook, New York 11794-3800, USA  A. Denisov  IHEP Protvino, State Research
Center of Russian Federation, Institute for High Energy Physics, Protvino,
142281, Russia  A. Deshpande  RIKEN BNL Research Center, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  Department of Physics and
Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
E.J. Desmond  Physics Department, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  L. Ding  Iowa State University, Ames, Iowa 50011, USA
J.H. Do  Yonsei University, IPAP, Seoul 120-749, Korea  L. D’Orazio
University of Maryland, College Park, Maryland 20742, USA  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, New York 11794-3800, USA
K.A. Drees  Collider-Accelerator Department, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  J.M. Durham  Los Alamos National Laboratory,
Los Alamos, New Mexico 87545, USA  A. Durum  IHEP Protvino, State Research
Center of Russian Federation, Institute for High Energy Physics, Protvino,
142281, Russia  T. Engelmore  Columbia University, New York, New York 10027
and Nevis Laboratories, Irvington, New York 10533, USA  A. Enokizono  RIKEN
Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo
171-8501, Japan  S. Esumi  Tomonaga Center for the History of the Universe,
University of Tsukuba, Tsukuba, Ibaraki 305, Japan  K.O. Eyser  Physics
Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
B. Fadem  Muhlenberg College, Allentown, Pennsylvania 18104-5586, USA  W. Fan
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony
Brook, New York 11794-3800, USA  N. Feege  Department of Physics and
Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
D.E. Fields  University of New Mexico, Albuquerque, New Mexico 87131, USA  M.
Finger  Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech
Republic  M. Finger, Jr  Charles University, Ovocný trh 5, Praha 1, 116 36,
Prague, Czech Republic  F. Fleuret  Laboratoire Leprince-Ringuet, Ecole
Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France  S.L.
Fokin  National Research Center “Kurchatov Institute”, Moscow, 123098 Russia
J.E. Frantz  Department of Physics and Astronomy, Ohio University, Athens,
Ohio 45701, USA  A. Franz  Physics Department, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  A.D. Frawley  Florida State University,
Tallahassee, Florida 32306, USA  Y. Fukao  KEK, High Energy Accelerator
Research Organization, Tsukuba, Ibaraki 305-0801, Japan  T. Fusayasu  Nagasaki
Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, Japan  K.
Gainey  Abilene Christian University, Abilene, Texas 79699, USA  C. Gal
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony
Brook, New York 11794-3800, USA  P. Gallus  Czech Technical University, Zikova
4, 166 36 Prague 6, Czech Republic  P. Garg  Department of Physics, Banaras
Hindu University, Varanasi 221005, India  Department of Physics and Astronomy,
Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA  A.
Garishvili  University of Tennessee, Knoxville, Tennessee 37996, USA  I.
Garishvili  Lawrence Livermore National Laboratory, Livermore, California
94550, USA  H. Ge  Department of Physics and Astronomy, Stony Brook
University, SUNY, Stony Brook, New York 11794-3800, USA  F. Giordano
University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA  A.
Glenn  Lawrence Livermore National Laboratory, Livermore, California 94550,
USA  X. Gong  Chemistry Department, Stony Brook University, SUNY, Stony Brook,
New York 11794-3400, USA  M. Gonin  Laboratoire Leprince-Ringuet, Ecole
Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France  Y.
Goto  RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama
351-0198, Japan  RIKEN BNL Research Center, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  R. Granier de Cassagnac  Laboratoire
Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128,
Palaiseau, France  N. Grau  Department of Physics, Augustana University, Sioux
Falls, South Dakota 57197, USA  S.V. Greene  Vanderbilt University, Nashville,
Tennessee 37235, USA  M. Grosse Perdekamp  University of Illinois at Urbana-
Champaign, Urbana, Illinois 61801, USA  Y. Gu  Chemistry Department, Stony
Brook University, SUNY, Stony Brook, New York 11794-3400, USA  T. Gunji
Center for Nuclear Study, Graduate School of Science, University of Tokyo,
7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  H. Guragain  Georgia State
University, Atlanta, Georgia 30303, USA  T. Hachiya  Nara Women’s University,
Kita-uoya Nishi-machi Nara 630-8506, Japan  RIKEN BNL Research Center,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  J.S. Haggerty
Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  K.I. Hahn  Ewha Womans University, Seoul 120-750, Korea  H.
Hamagaki  Center for Nuclear Study, Graduate School of Science, University of
Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  J. Hanks  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  S. Hasegawa  Advanced Science Research Center, Japan Atomic
Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki-ken
319-1195, Japan  T.O.S. Haseler  Georgia State University, Atlanta, Georgia
30303, USA  K. Hashimoto  RIKEN Nishina Center for Accelerator-Based Science,
Wako, Saitama 351-0198, Japan  Physics Department, Rikkyo University, 3-34-1
Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan  R. Hayano  Center for Nuclear
Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo,
Tokyo 113-0033, Japan  X. He  Georgia State University, Atlanta, Georgia
30303, USA  T.K. Hemmick  Department of Physics and Astronomy, Stony Brook
University, SUNY, Stony Brook, New York 11794-3800, USA  T. Hester  University
of California-Riverside, Riverside, California 92521, USA  J.C. Hill  Iowa
State University, Ames, Iowa 50011, USA  K. Hill  University of Colorado,
Boulder, Colorado 80309, USA  A. Hodges  Georgia State University, Atlanta,
Georgia 30303, USA  R.S. Hollis  University of California-Riverside,
Riverside, California 92521, USA  K. Homma  Hiroshima University, Kagamiyama,
Higashi-Hiroshima 739-8526, Japan  B. Hong  Korea University, Seoul, 136-701,
Korea  T. Hoshino  Hiroshima University, Kagamiyama, Higashi-Hiroshima
739-8526, Japan  N. Hotvedt  Iowa State University, Ames, Iowa 50011, USA  J.
Huang  Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  Los Alamos National Laboratory, Los Alamos, New Mexico 87545,
USA  S. Huang  Vanderbilt University, Nashville, Tennessee 37235, USA  T.
Ichihara  RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama
351-0198, Japan  RIKEN BNL Research Center, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  Y. Ikeda  RIKEN Nishina Center for
Accelerator-Based Science, Wako, Saitama 351-0198, Japan  K. Imai  Advanced
Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane,
Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan  Y. Imazu  RIKEN Nishina
Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan  M. Inaba
Tomonaga Center for the History of the Universe, University of Tsukuba,
Tsukuba, Ibaraki 305, Japan  A. Iordanova  University of California-Riverside,
Riverside, California 92521, USA  D. Isenhower  Abilene Christian University,
Abilene, Texas 79699, USA  A. Isinhue  Muhlenberg College, Allentown,
Pennsylvania 18104-5586, USA  D. Ivanishchev  PNPI, Petersburg Nuclear Physics
Institute, Gatchina, Leningrad region, 188300, Russia  B.V. Jacak  Department
of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  S.J. Jeon  Myongji University, Yongin, Kyonggido 449-728,
Korea  M. Jezghani  Georgia State University, Atlanta, Georgia 30303, USA  Z.
Ji  Department of Physics and Astronomy, Stony Brook University, SUNY, Stony
Brook, New York 11794-3800, USA  J. Jia  Physics Department, Brookhaven
National Laboratory, Upton, New York 11973-5000, USA  Chemistry Department,
Stony Brook University, SUNY, Stony Brook, New York 11794-3400, USA  X. Jiang
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA  B.M.
Johnson  Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  Georgia State University, Atlanta, Georgia 30303, USA  K.S.
Joo  Myongji University, Yongin, Kyonggido 449-728, Korea  D. Jouan  IPN-
Orsay, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, BP1, F-91406,
Orsay, France  D.S. Jumper  University of Illinois at Urbana-Champaign,
Urbana, Illinois 61801, USA  J. Kamin  Department of Physics and Astronomy,
Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA  S. Kanda
Center for Nuclear Study, Graduate School of Science, University of Tokyo,
7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  KEK, High Energy Accelerator
Research Organization, Tsukuba, Ibaraki 305-0801, Japan  B.H. Kang  Hanyang
University, Seoul 133-792, Korea  J.H. Kang  Yonsei University, IPAP, Seoul
120-749, Korea  J.S. Kang  Hanyang University, Seoul 133-792, Korea  J.
Kapustinsky  Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
D. Kawall  Department of Physics, University of Massachusetts, Amherst,
Massachusetts 01003-9337, USA  A.V. Kazantsev  National Research Center
“Kurchatov Institute”, Moscow, 123098 Russia  J.A. Key  University of New
Mexico, Albuquerque, New Mexico 87131, USA  V. Khachatryan  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  P.K. Khandai  Department of Physics, Banaras Hindu
University, Varanasi 221005, India  A. Khanzadeev  PNPI, Petersburg Nuclear
Physics Institute, Gatchina, Leningrad region, 188300, Russia  K.M. Kijima
Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan  C. Kim
Korea University, Seoul, 136-701, Korea  D.J. Kim  Helsinki Institute of
Physics and University of Jyväskylä, P.O.Box 35, FI-40014 Jyväskylä, Finland
E.-J. Kim  Chonbuk National University, Jeonju, 561-756, Korea  M. Kim
Department of Physics and Astronomy, Seoul National University, Seoul 151-742,
Korea  Y.-J. Kim  University of Illinois at Urbana-Champaign, Urbana, Illinois
61801, USA  Y.K. Kim  Hanyang University, Seoul 133-792, Korea  D. Kincses
ELTE, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/A, Hungary
E. Kistenev  Physics Department, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  J. Klatsky  Florida State University, Tallahassee,
Florida 32306, USA  D. Kleinjan  University of California-Riverside,
Riverside, California 92521, USA  P. Kline  Department of Physics and
Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
T. Koblesky  University of Colorado, Boulder, Colorado 80309, USA  M. Kofarago
ELTE, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/A, Hungary
Institute for Particle and Nuclear Physics, Wigner Research Centre for
Physics, Hungarian Academy of Sciences (Wigner RCP, RMKI) H-1525 Budapest 114,
POBox 49, Budapest, Hungary  B. Komkov  PNPI, Petersburg Nuclear Physics
Institute, Gatchina, Leningrad region, 188300, Russia  J. Koster  RIKEN BNL
Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000,
USA  D. Kotchetkov  Department of Physics and Astronomy, Ohio University,
Athens, Ohio 45701, USA  D. Kotov  PNPI, Petersburg Nuclear Physics Institute,
Gatchina, Leningrad region, 188300, Russia  Saint Petersburg State Polytechnic
University, St. Petersburg, 195251 Russia  F. Krizek  Helsinki Institute of
Physics and University of Jyväskylä, P.O.Box 35, FI-40014 Jyväskylä, Finland
B. Kurgyis  ELTE, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s.
1/A, Hungary  K. Kurita  Physics Department, Rikkyo University, 3-34-1 Nishi-
Ikebukuro, Toshima, Tokyo 171-8501, Japan  M. Kurosawa  RIKEN Nishina Center
for Accelerator-Based Science, Wako, Saitama 351-0198, Japan  RIKEN BNL
Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000,
USA  Y. Kwon  Yonsei University, IPAP, Seoul 120-749, Korea  R. Lacey
Chemistry Department, Stony Brook University, SUNY, Stony Brook, New York
11794-3400, USA  Y.S. Lai  Columbia University, New York, New York 10027 and
Nevis Laboratories, Irvington, New York 10533, USA  J.G. Lajoie  Iowa State
University, Ames, Iowa 50011, USA  A. Lebedev  Iowa State University, Ames,
Iowa 50011, USA  D.M. Lee  Los Alamos National Laboratory, Los Alamos, New
Mexico 87545, USA  G.H. Lee  Chonbuk National University, Jeonju, 561-756,
Korea  J. Lee  Ewha Womans University, Seoul 120-750, Korea  Sungkyunkwan
University, Suwon, 440-746, Korea  K.B. Lee  Los Alamos National Laboratory,
Los Alamos, New Mexico 87545, USA  K.S. Lee  Korea University, Seoul, 136-701,
Korea  S.H. Lee  Iowa State University, Ames, Iowa 50011, USA  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  M.J. Leitch  Los Alamos National Laboratory, Los Alamos, New
Mexico 87545, USA  M. Leitgab  University of Illinois at Urbana-Champaign,
Urbana, Illinois 61801, USA  Y.H. Leung  Department of Physics and Astronomy,
Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA  B. Lewis
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony
Brook, New York 11794-3800, USA  N.A. Lewis  Department of Physics, University
of Michigan, Ann Arbor, Michigan 48109-1040, USA  X. Li  Science and
Technology on Nuclear Data Laboratory, China Institute of Atomic Energy,
Beijing 102413, People’s Republic of China  X. Li  Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, USA  S.H. Lim  Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, USA  Yonsei University, IPAP, Seoul
120-749, Korea  M.X. Liu  Los Alamos National Laboratory, Los Alamos, New
Mexico 87545, USA  S. Lökös  ELTE, Eötvös Loránd University, H-1117 Budapest,
Pázmány P. s. 1/A, Hungary  Eszterházy Károly University, Károly Róbert
Campus, H-3200 Gyöngyös, Mátrai út 36, Hungary  D. Lynch  Physics Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  C.F. Maguire
Vanderbilt University, Nashville, Tennessee 37235, USA  T. Majoros  Debrecen
University, H-4010 Debrecen, Egyetem tér 1, Hungary  Y.I. Makdisi  Collider-
Accelerator Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  M. Makek  Weizmann Institute, Rehovot 76100, Israel
Department of Physics, Faculty of Science, University of Zagreb, Bijenička c.
32 HR-10002 Zagreb, Croatia  A. Manion  Department of Physics and Astronomy,
Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA  V.I.
Manko  National Research Center “Kurchatov Institute”, Moscow, 123098 Russia
E. Mannel  Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  M. McCumber  University of Colorado, Boulder, Colorado 80309,
USA  Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA  P.L.
McGaughey  Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
D. McGlinchey  University of Colorado, Boulder, Colorado 80309, USA  Florida
State University, Tallahassee, Florida 32306, USA  Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, USA  C. McKinney  University of
Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA  A. Meles  New
Mexico State University, Las Cruces, New Mexico 88003, USA  M. Mendoza
University of California-Riverside, Riverside, California 92521, USA  B.
Meredith  University of Illinois at Urbana-Champaign, Urbana, Illinois 61801,
USA  Y. Miake  Tomonaga Center for the History of the Universe, University of
Tsukuba, Tsukuba, Ibaraki 305, Japan  T. Mibe  KEK, High Energy Accelerator
Research Organization, Tsukuba, Ibaraki 305-0801, Japan  A.C. Mignerey
University of Maryland, College Park, Maryland 20742, USA  D.E. Mihalik
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony
Brook, New York 11794-3800, USA  A. Milov  Weizmann Institute, Rehovot 76100,
Israel  D.K. Mishra  Bhabha Atomic Research Centre, Bombay 400 085, India
J.T. Mitchell  Physics Department, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  G. Mitsuka  KEK, High Energy Accelerator Research
Organization, Tsukuba, Ibaraki 305-0801, Japan  RIKEN BNL Research Center,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  S. Miyasaka
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  S. Mizuno  RIKEN Nishina Center for
Accelerator-Based Science, Wako, Saitama 351-0198, Japan  Tomonaga Center for
the History of the Universe, University of Tsukuba, Tsukuba, Ibaraki 305,
Japan  A.K. Mohanty  Bhabha Atomic Research Centre, Bombay 400 085, India  S.
Mohapatra  Chemistry Department, Stony Brook University, SUNY, Stony Brook,
New York 11794-3400, USA  T. Moon  Yonsei University, IPAP, Seoul 120-749,
Korea  D.P. Morrison  Physics Department, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  S.I. Morrow  Vanderbilt University,
Nashville, Tennessee 37235, USA  M. Moskowitz  Muhlenberg College, Allentown,
Pennsylvania 18104-5586, USA  T.V. Moukhanova  National Research Center
“Kurchatov Institute”, Moscow, 123098 Russia  T. Murakami  Kyoto University,
Kyoto 606-8502, Japan  RIKEN Nishina Center for Accelerator-Based Science,
Wako, Saitama 351-0198, Japan  J. Murata  RIKEN Nishina Center for
Accelerator-Based Science, Wako, Saitama 351-0198, Japan  Physics Department,
Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan  A.
Mwai  Chemistry Department, Stony Brook University, SUNY, Stony Brook, New
York 11794-3400, USA  T. Nagae  Kyoto University, Kyoto 606-8502, Japan  S.
Nagamiya  KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki
305-0801, Japan  RIKEN Nishina Center for Accelerator-Based Science, Wako,
Saitama 351-0198, Japan  K. Nagashima  Hiroshima University, Kagamiyama,
Higashi-Hiroshima 739-8526, Japan  J.L. Nagle  University of Colorado,
Boulder, Colorado 80309, USA  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, New York 11973-5000,
USA  Y. Nakamiya  Hiroshima University, Kagamiyama, Higashi-Hiroshima
739-8526, Japan  K.R. Nakamura  Kyoto University, Kyoto 606-8502, Japan  RIKEN
Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
T. Nakamura  RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama
351-0198, 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  C. Nattrass
University of Tennessee, Knoxville, Tennessee 37996, USA  P.K. Netrakanti
Bhabha Atomic Research Centre, Bombay 400 085, India  M. Nihashi  Hiroshima
University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan  RIKEN Nishina
Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan  T. Niida
Tomonaga Center for the History of the Universe, University of Tsukuba,
Tsukuba, Ibaraki 305, Japan  R. Nouicer  Physics Department, Brookhaven
National Laboratory, Upton, New York 11973-5000, USA  RIKEN BNL Research
Center, Brookhaven National Laboratory, Upton, New York 11973-5000, USA  T.
Novák  Eszterházy Károly University, Károly Róbert Campus, H-3200 Gyöngyös,
Mátrai út 36, Hungary  Institute for Particle and Nuclear Physics, Wigner
Research Centre for Physics, Hungarian Academy of Sciences (Wigner RCP, RMKI)
H-1525 Budapest 114, POBox 49, Budapest, Hungary  N. Novitzky  Helsinki
Institute of Physics and University of Jyväskylä, P.O.Box 35, FI-40014
Jyväskylä, Finland  Department of Physics and Astronomy, Stony Brook
University, SUNY, Stony Brook, New York 11794-3800, USA  A.S. Nyanin  National
Research Center “Kurchatov Institute”, Moscow, 123098 Russia  E. O’Brien
Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  C.A. Ogilvie  Iowa State University, Ames, Iowa 50011, USA
H. Oide  Center for Nuclear Study, Graduate School of Science, University of
Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  K. Okada  RIKEN BNL
Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000,
USA  J.D. Orjuela Koop  University of Colorado, Boulder, Colorado 80309, USA
J.D. Osborn  Department of Physics, University of Michigan, Ann Arbor,
Michigan 48109-1040, USA  A. Oskarsson  Department of Physics, Lund
University, Box 118, SE-221 00 Lund, Sweden  K. Ozawa  KEK, High Energy
Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan  Tomonaga
Center for the History of the Universe, University of Tsukuba, Tsukuba,
Ibaraki 305, Japan  R. Pak  Physics Department, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  V. Pantuev  Institute for Nuclear
Research of the Russian Academy of Sciences, prospekt 60-letiya Oktyabrya 7a,
Moscow 117312, Russia  V. Papavassiliou  New Mexico State University, Las
Cruces, New Mexico 88003, USA  I.H. Park  Ewha Womans University, Seoul
120-750, Korea  Sungkyunkwan University, Suwon, 440-746, Korea  S. Park  RIKEN
Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
Department of Physics and Astronomy, Seoul National University, Seoul 151-742,
Korea  Department of Physics and Astronomy, Stony Brook University, SUNY,
Stony Brook, New York 11794-3800, USA  S.K. Park  Korea University, Seoul,
136-701, Korea  S.F. Pate  New Mexico State University, Las Cruces, New Mexico
88003, USA  L. Patel  Georgia State University, Atlanta, Georgia 30303, USA
M. Patel  Iowa State University, Ames, Iowa 50011, USA  J.-C. Peng  University
of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA  W. Peng
Vanderbilt University, Nashville, Tennessee 37235, USA  D.V. Perepelitsa
University of Colorado, Boulder, Colorado 80309, USA  Columbia University, New
York, New York 10027 and Nevis Laboratories, Irvington, New York 10533, USA
G.D.N. Perera  New Mexico State University, Las Cruces, New Mexico 88003, USA
D.Yu. Peressounko  National Research Center “Kurchatov Institute”, Moscow,
123098 Russia  C.E. PerezLara  Department of Physics and Astronomy, Stony
Brook University, SUNY, Stony Brook, New York 11794-3800, USA  J. Perry  Iowa
State University, Ames, Iowa 50011, USA  R. Petti  Physics Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  C. Pinkenburg  Physics Department, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  R.P. Pisani  Physics Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  M.L. Purschke
Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  H. Qu  Abilene Christian University, Abilene, Texas 79699,
USA  P.V. Radzevich  Saint Petersburg State Polytechnic University, St.
Petersburg, 195251 Russia  J. Rak  Helsinki Institute of Physics and
University of Jyväskylä, P.O.Box 35, FI-40014 Jyväskylä, Finland  I.
Ravinovich  Weizmann Institute, Rehovot 76100, Israel  K.F. Read  Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, USA  University of Tennessee,
Knoxville, Tennessee 37996, USA  D. Reynolds  Chemistry Department, Stony
Brook University, SUNY, Stony Brook, New York 11794-3400, USA  V. Riabov
National Research Nuclear University, MEPhI, Moscow Engineering Physics
Institute, Moscow, 115409, Russia  PNPI, Petersburg Nuclear Physics Institute,
Gatchina, Leningrad region, 188300, Russia  Y. Riabov  PNPI, Petersburg
Nuclear Physics Institute, Gatchina, Leningrad region, 188300, Russia  Saint
Petersburg State Polytechnic University, St. Petersburg, 195251 Russia  E.
Richardson  University of Maryland, College Park, Maryland 20742, USA  D.
Richford  Baruch College, City University of New York, New York, New York,
10010 USA  T. Rinn  Iowa State University, Ames, Iowa 50011, USA  N. Riveli
Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
D. Roach  Vanderbilt University, Nashville, Tennessee 37235, USA  S.D. Rolnick
University of California-Riverside, Riverside, California 92521, USA  M.
Rosati  Iowa State University, Ames, Iowa 50011, USA  Z. Rowan  Baruch
College, City University of New York, New York, New York, 10010 USA  J.
Runchey  Iowa State University, Ames, Iowa 50011, USA  M.S. Ryu  Hanyang
University, Seoul 133-792, Korea  B. Sahlmueller  Department of Physics and
Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
N. Saito  KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki
305-0801, Japan  T. Sakaguchi  Physics Department, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  H. Sako  Advanced Science
Research Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-
mura, Naka-gun, Ibaraki-ken 319-1195, Japan  V. Samsonov  National Research
Nuclear University, MEPhI, Moscow Engineering Physics Institute, Moscow,
115409, Russia  PNPI, Petersburg Nuclear Physics Institute, Gatchina,
Leningrad region, 188300, Russia  M. Sarsour  Georgia State University,
Atlanta, Georgia 30303, USA  S. Sato  Advanced Science Research Center, Japan
Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki-ken
319-1195, Japan  S. Sawada  KEK, High Energy Accelerator Research
Organization, Tsukuba, Ibaraki 305-0801, Japan  B.K. Schmoll  University of
Tennessee, Knoxville, Tennessee 37996, USA  K. Sedgwick  University of
California-Riverside, Riverside, California 92521, USA  J. Seele  RIKEN BNL
Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000,
USA  R. Seidl  RIKEN Nishina Center for Accelerator-Based Science, Wako,
Saitama 351-0198, Japan  RIKEN BNL Research Center, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  Y. Sekiguchi  Center for Nuclear
Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo,
Tokyo 113-0033, Japan  A. Sen  Georgia State University, Atlanta, Georgia
30303, USA  Iowa State University, Ames, Iowa 50011, USA  R. Seto  University
of California-Riverside, Riverside, California 92521, USA  P. Sett  Bhabha
Atomic Research Centre, Bombay 400 085, India  D. Sharma  Department of
Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York
11794-3800, USA  A. Shaver  Iowa State University, Ames, Iowa 50011, USA  I.
Shein  IHEP Protvino, State Research Center of Russian Federation, Institute
for High Energy Physics, Protvino, 142281, Russia  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  Iowa State University, Ames, Iowa
50011, USA  Nara Women’s University, Kita-uoya Nishi-machi Nara 630-8506,
Japan  K. Shoji  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, New York 11973-5000, USA  University of Illinois at Urbana-Champaign,
Urbana, Illinois 61801, USA  C.L. Silva  Los Alamos National Laboratory, Los
Alamos, New Mexico 87545, USA  D. Silvermyr  Department of Physics, Lund
University, Box 118, SE-221 00 Lund, Sweden  Oak Ridge National Laboratory,
Oak Ridge, Tennessee 37831, USA  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  M.J. Skoby
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040,
USA  M. Skolnik  Muhlenberg College, Allentown, Pennsylvania 18104-5586, USA
M. Slunečka  Charles University, Ovocný trh 5, Praha 1, 116 36, Prague, Czech
Republic  S. Solano  Muhlenberg College, Allentown, Pennsylvania 18104-5586,
USA  R.A. Soltz  Lawrence Livermore National Laboratory, Livermore, California
94550, USA  W.E. Sondheim  Los Alamos National Laboratory, Los Alamos, New
Mexico 87545, USA  S.P. Sorensen  University of Tennessee, Knoxville,
Tennessee 37996, USA  I.V. Sourikova  Physics Department, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  P.W. Stankus  Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37831, USA  P. Steinberg  Physics Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  E. Stenlund
Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden  M.
Stepanov  Deceased  Department of Physics, University of Massachusetts,
Amherst, Massachusetts 01003-9337, USA  A. Ster  Institute for Particle and
Nuclear Physics, Wigner Research Centre for Physics, Hungarian Academy of
Sciences (Wigner RCP, RMKI) H-1525 Budapest 114, POBox 49, Budapest, Hungary
S.P. Stoll  Physics Department, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  M.R. Stone  University of Colorado, Boulder, Colorado
80309, USA  T. Sugitate  Hiroshima University, Kagamiyama, Higashi-Hiroshima
739-8526, Japan  A. Sukhanov  Physics Department, Brookhaven National
Laboratory, Upton, New York 11973-5000, USA  J. Sun  Department of Physics and
Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
Z. Sun  Debrecen University, H-4010 Debrecen, Egyetem tér 1, Hungary  A.
Takahara  Center for Nuclear Study, Graduate School of Science, University of
Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  A. Taketani  RIKEN Nishina
Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan  RIKEN BNL
Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000,
USA  Y. Tanaka  Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki
851-0193, Japan  K. Tanida  Advanced Science Research Center, Japan Atomic
Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki-ken
319-1195, Japan  RIKEN BNL Research Center, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  Department of Physics and Astronomy, Seoul
National University, Seoul 151-742, Korea  M.J. Tannenbaum  Physics
Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
S. Tarafdar  Department of Physics, Banaras Hindu University, Varanasi 221005,
India  Vanderbilt University, Nashville, Tennessee 37235, USA  A. Taranenko
National Research Nuclear University, MEPhI, Moscow Engineering Physics
Institute, Moscow, 115409, Russia  Chemistry Department, Stony Brook
University, SUNY, Stony Brook, New York 11794-3400, USA  E. Tennant  New
Mexico State University, Las Cruces, New Mexico 88003, USA  R. Tieulent  IPNL,
CNRS/IN2P3, Univ Lyon, Université Lyon 1, F-69622, Villeurbanne, France  A.
Timilsina  Iowa State University, Ames, Iowa 50011, USA  T. Todoroki  RIKEN
Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  Tomonaga Center for the History of the Universe, University
of Tsukuba, Tsukuba, Ibaraki 305, Japan  M. Tomášek  Czech Technical
University, Zikova 4, 166 36 Prague 6, Czech Republic  Institute of Physics,
Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8,
Czech Republic  H. Torii  Center for Nuclear Study, Graduate School of
Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan  R.S.
Towell  Abilene Christian University, Abilene, Texas 79699, USA  I. Tserruya
Weizmann Institute, Rehovot 76100, Israel  Y. Ueda  Hiroshima University,
Kagamiyama, Higashi-Hiroshima 739-8526, Japan  B. Ujvari  Debrecen University,
H-4010 Debrecen, Egyetem tér 1, Hungary  H.W. van Hecke  Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, USA  M. Vargyas  ELTE, Eötvös Loránd
University, H-1117 Budapest, Pázmány P. s. 1/A, Hungary  Institute for
Particle and Nuclear Physics, Wigner Research Centre for Physics, Hungarian
Academy of Sciences (Wigner RCP, RMKI) H-1525 Budapest 114, POBox 49,
Budapest, Hungary  E. Vazquez-Zambrano  Columbia University, New York, New
York 10027 and Nevis Laboratories, Irvington, New York 10533, USA  A. Veicht
Columbia University, New York, New York 10027 and Nevis Laboratories,
Irvington, New York 10533, USA  J. Velkovska  Vanderbilt University,
Nashville, Tennessee 37235, USA  R. Vértesi  Institute for Particle and
Nuclear Physics, Wigner Research Centre for Physics, Hungarian Academy of
Sciences (Wigner RCP, RMKI) H-1525 Budapest 114, POBox 49, Budapest, Hungary
M. Virius  Czech Technical University, Zikova 4, 166 36 Prague 6, Czech
Republic  V. Vrba  Czech Technical University, Zikova 4, 166 36 Prague 6,
Czech Republic  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  X.R. Wang  New Mexico State University, Las Cruces, New Mexico 88003,
USA  RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  D. Watanabe  Hiroshima University, Kagamiyama, Higashi-
Hiroshima 739-8526, Japan  K. Watanabe  RIKEN Nishina Center for Accelerator-
Based Science, Wako, Saitama 351-0198, Japan  Physics Department, Rikkyo
University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan  Y.
Watanabe  RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama
351-0198, Japan  RIKEN BNL Research Center, Brookhaven National Laboratory,
Upton, New York 11973-5000, USA  Y.S. Watanabe  Center for Nuclear Study,
Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo
113-0033, Japan  KEK, High Energy Accelerator Research Organization, Tsukuba,
Ibaraki 305-0801, Japan  F. Wei  New Mexico State University, Las Cruces, New
Mexico 88003, USA  S. Whitaker  Iowa State University, Ames, Iowa 50011, USA
S. Wolin  University of Illinois at Urbana-Champaign, Urbana, Illinois 61801,
USA  C.P. Wong  Georgia State University, Atlanta, Georgia 30303, USA  C.L.
Woody  Physics Department, Brookhaven National Laboratory, Upton, New York
11973-5000, USA  M. Wysocki  Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, USA  B. Xia  Department of Physics and Astronomy, Ohio
University, Athens, Ohio 45701, USA  C. Xu  New Mexico State University, Las
Cruces, New Mexico 88003, USA  Q. Xu  Vanderbilt University, Nashville,
Tennessee 37235, USA  Y.L. Yamaguchi  Center for Nuclear Study, Graduate
School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033,
Japan  RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New
York 11973-5000, USA  Department of Physics and Astronomy, Stony Brook
University, SUNY, Stony Brook, New York 11794-3800, USA  A. Yanovich  IHEP
Protvino, State Research Center of Russian Federation, Institute for High
Energy Physics, Protvino, 142281, Russia  S. Yokkaichi  RIKEN Nishina Center
for Accelerator-Based Science, Wako, Saitama 351-0198, Japan  RIKEN BNL
Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000,
USA  J.H. Yoo  Korea University, Seoul, 136-701, Korea  I. Yoon  Department of
Physics and Astronomy, Seoul National University, Seoul 151-742, Korea  Z. You
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA  I. Younus
Physics Department, Lahore University of Management Sciences, Lahore 54792,
Pakistan  University of New Mexico, Albuquerque, New Mexico 87131, USA  H. Yu
New Mexico State University, Las Cruces, New Mexico 88003, USA  Peking
University, Beijing 100871, People’s Republic of China  I.E. Yushmanov
National Research Center “Kurchatov Institute”, Moscow, 123098 Russia  W.A.
Zajc  Columbia University, New York, New York 10027 and Nevis Laboratories,
Irvington, New York 10533, USA  A. Zelenski  Collider-Accelerator Department,
Brookhaven National Laboratory, Upton, New York 11973-5000, USA  S. Zharko
Saint Petersburg State Polytechnic University, St. Petersburg, 195251 Russia
S. Zhou  Science and Technology on Nuclear Data Laboratory, China Institute of
Atomic Energy, Beijing 102413, People’s Republic of China  L. Zou  University
of California-Riverside, Riverside, California 92521, USA

###### Abstract

Production of $\pi^{0}$ and $\eta$ mesons has been measured at midrapidity in
Cu$+$Au collisions at $\sqrt{s_{{}_{NN}}}$=200 GeV. Measurements were
performed in $\pi^{0}(\eta)\rightarrow\gamma\gamma$ decay channel in the
1(2)-20 GeV/$c$ transverse momentum range. A strong suppression is observed
for $\pi^{0}$ and $\eta$ meson production at high transverse momentum in
central Cu$+$Au collisions relative to the $p$$+$$p$ results scaled by the
number of nucleon-nucleon collisions. In central collisions the suppression is
similar to Au$+$Au with comparable nuclear overlap. The $\eta/\pi^{0}$ ratio
measured as a function of transverse momentum is consistent with
$m_{T}$-scaling parameterization down to $p_{T}=2$ GeV/$c$, its asymptotic
value is constant and consistent with Au$+$Au and $p$$+$$p$ and does not show
any significant dependence on collision centrality. Similar results were
obtained in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions as
well as in $e^{+}e^{-}$ collisions in a range of collision energies
$\sqrt{s_{{}_{NN}}}=3$–1800 GeV. This suggests that the quark-gluon-plasma
medium produced in Cu$+$Cu collisions either does not affect the jet
fragmentation into light mesons or it affects the $\pi^{0}$ and $\eta$ the
same way.

##  I Introduction

Experiments at the Relativistic Heavy Ion Collider (RHIC) Arsene  _et al._
(2005); Back  _et al._ (2005); Adams  _et al._ (2005); Adcox  _et al._ (2005)
and later at the Large Hadron Collider (LHC) Chatrchyan  _et al._ (2012);
Abelev  _et al._ (2013); Aad  _et al._ (2013); Gunji (2016) established the
formation of quark-gluon plasma (QGP) in relativistic collisions of heavy ions
(A$+$A). One of the most important tools to investigate the properties of this
new medium are identified hadrons at high transverse momenta ($p_{T}$ $>$5
GeV/$c$), because they are leading fragments Jacob and Landshoff (1978) of
jets from hard-scattered partons, which, before fragmentation, interacted with
the QGP Baier  _et al._ (2000). The differential cross section of high-$p_{T}$
hadron production in elementary $p$+$p$ collisions can be derived using next-
to-leading-order perturbative-quantum-chromodynamics formalism Owens (1987);
Adare  _et al._ (2007):

$\displaystyle d\sigma_{pp\rightarrow hX}\approx\sum_{abcd}\int
dx_{a}dx_{b}dz_{c}f_{a/p}(x_{a})\otimes f_{b/p}(x_{b})$ (1)
$\displaystyle\otimes\ d\sigma_{ab\rightarrow cd}\otimes D_{c\rightarrow
h}(z_{c}),$

where $x_{a,b}$ is the initial momentum fraction carried by partons $a$ and
$b$, $z_{c}$ is the final-state momentum fraction of the hadron $h$, $f_{a/p}$
and $f_{b/p}$ are the parton distribution functions (PDFs),
$d\sigma_{ab\rightarrow cd}$ is the differential cross section of the initial
partons hard scattering, $D_{c\rightarrow h}$ is the fragmentation function
(FF) of the hard scattered parton to the final-state hadron.

There are two classes of nuclear effects, which modify the high-$p_{T}$ hadron
production cross section in A+A collisions. The initial state (or cold nuclear
matter) effects are related to the presence of a heavy nucleus in the
collision and require the modification of the corresponding PDF in Eq. 1. The
correction factors for PDFs are usually obtained from the $p$/$d$$+$$A$ data
Helenius  _et al._ ; Eskola  _et al._ (2017).

The final-state effects are related to the formation of a hot, dense medium,
QGP. While the hard-scattered parton propagates through the medium, it loses a
fraction of its energy (jet-quenching) Bjorken (1982); Baier  _et al._ (2000);
Wang  _et al._ (1995) by gluon emission or elastic scatterings with the medium
constituents.

Parton energy loss in the QGP is quantified with the jet transport coefficient
$\hat{q}$, defined as the squared momentum exchange between the hard parton
and the medium per unit path length Baier  _et al._ (2000). The relation of
$\hat{q}$ to other medium parameters, such as temperature, shear viscosity and
entropy, is indicative of the character of the coupling to the medium Majumder
_et al._ (2007).

Several phenomenological models Qin  _et al._ (2008); Chen  _et al._ (2011);
Young  _et al._ (2012); Majumder and Shen (2012); Xu  _et al._ (2014) were
designed to estimate $\hat{q}$ based on $R_{AB}$ measurements at RHIC and the
LHC. In the model calculations, the final state effects are usually accounted
for by replacing $D_{c\rightarrow h}$ with the medium-modified FF
$\widetilde{D}_{c\rightarrow h}$ in Eq. 1. Methods of
$\widetilde{D}_{c\rightarrow h}$ estimation are specific for each parton
energy model. Also several attempts were made to extract $\hat{q}$ using
lattice QCD calculations Majumder (2013); Panero  _et al._ (2014). The effects
of the medium on particle production are usually quantified by the nuclear
modification factor ($R_{AB}$):

$R_{AB}^{\rm cent}(\mbox{$p_{T}$})=\frac{1}{T_{AB}^{\rm
cent}}\frac{dN_{AB}^{\rm
cent}/d\mbox{$p_{T}$}}{d\sigma_{pp}/d\mbox{$p_{T}$}},$ (2)

where $dN_{AB}^{\rm cent}$ is the particle yield measured in A+B collisions
for a given centrality class ($cent$), $d\sigma_{pp}$ is the cross section of
the same particle measured in $p$$+$$p$ collisions at the same collision
energy, $T_{AB}^{\rm cent}$ is the nuclear thickness function for the event
class Miller  _et al._ (2007). The energy loss of hard-scattered partons
causes a reduction of $R_{AB}$ from unity towards smaller values.

Measurement of $\pi^{0}$ meson production is particularly interesting, because
$\pi^{0}$s are abundantly produced and their yields can be measured up to high
$p_{T}$ with good particle identification, an excellent signal-to-background
ratio ($S/B$), and relatively small uncertainties using the electromagnetic
calorimeters (EMCal) of the PHENIX detector. The $\eta$ meson has four times
heavier mass than $\pi^{0}$ and an about 50% strangeness content. Thus
measurements of $\eta$ allow to study the dependence of jet quenching on the
hadron mass and flavor content. Measurement of $\eta/\pi^{0}$ in A$+$A gives
an opportunity to better understand whether fragmentation processes are
affected by the presence of the colored medium.

Previously published results on $\pi^{0}$ and $\eta$ production at PHENIX were
obtained in symmetric heavy-ion systems such as Au$+$Au and Cu$+$Cu Adler  _et
al._ (2007); Adare  _et al._ (2008a, b, c, 2010). Contrarily to that, Cu$+$Au
collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV is the first asymmetric system of
heavy nuclei studied at RHIC. Such collisions provide a different collision
geometry from the one realized in symmetric systems. In central collisions the
Cu nucleus is fully submerged in the Au nucleus, which results in the
reduction of nucleon-nucleon interactions in the “corona” region Pantuev
(2007) of the collision (see Fig. 1). In semi-central Cu$+$Au collisions an
asymmetry of the nuclear overlap region is present along the axis connecting
the centers of the interacting nuclei. These features make Cu$+$Au collision
system an important part of the systematic study of the final-state effects in
heavy-ion collisions.

In this paper we present $\pi^{0}$ and $\eta$ meson $p_{T}$ spectra and
nuclear modification factor measurements in Cu$+$Au collisions at
$\sqrt{s_{{}_{NN}}}=200$ GeV. Data were collected in RHIC Year-2012 run with
the PHENIX detector.

##  II Data analysis

Figure 1: Cartoon showing Au$+$Au and Cu$+$Au collisions with comparable $N_{\rm part}$. On panel (b) the overlap area is asymmetric, and part of the dilute surfaces of Au and Cu (corona) overlap.  Table 1:  The average values of the nuclear thickness function $\left\langle T_{AB}\right\rangle$ and the numbers of nucleons participating in the nuclei interaction $\left\langle N_{\rm part}\right\rangle$ in different Cu$+$Au centrality intervals.  Centrality interval |  $\left\langle T_{AB}\right\rangle$ (mb-1) | $\left\langle N_{\rm part}\right\rangle$
---|---|---
Minimum Bias | $2.54\pm 0.19$ | $61.1\pm 2.7$
0%–10% | $8.8\pm 0.6$ | $177.2\pm 5.2$
10%–20% | $6.0\pm 0.4$ | $132.4\pm 3.7$
0%–20% | $7.5\pm 0.5$ | $154.8\pm 4.1$
20%–40% | $3.1\pm 0.2$ | $80.4\pm 3.3$
40%–60% | $1.00\pm 0.12$ | $34.9\pm 2.8$

A detailed description of the PHENIX experimental set-up can be found
elsewhere Adcox  _et al._ (2003). Beam-beam counters (BBC, $3.0<|\eta|<3.9$)
Allen  _et al._ (2003) located downstream in both beam directions (north and
south), each consisting of 64 Čerenkov-radiator counters, provide the minimum-
bias (MB) trigger Adler  _et al._ (2003) and are also used to determine the
event centrality and vertex position along the beam axis ($z_{\rm BBC}$). The
MB trigger is formed if two or more BBC counters on each side detect the
passage of charged particle(s). The MB trigger efficiency in Cu$+$Au is 93% of
total inelastic collisions. The event centrality is defined by the total
charge observed in the BBC. The mean number of participating nucleons ($N_{\rm
part}$), binary collisions ($N_{\rm coll}$) and the nuclear overlap function
($T_{AB}$) in various centrality intervals are estimated with a Glauber-model
Monte-Carlo simulation Miller  _et al._ (2007) folded with the BBC response.
The average values of $T_{AB}$ and $N_{\rm part}$ for different centrality
classes of Cu$+$Au collisions are listed in Table 1.

The measurements are based on two data sets. Up to moderate $p_{T}$ ($<8$
GeV/$c$) $6.9\times 10^{9}$ MB events satisfying a vertex cut of $|z_{\rm
BBC}|<20$ cm are used. To improve statistics and extend the range to higher
$p_{T}$ an additional sample was collected with one of the EMCal hardware
triggers (ERT-A). This trigger required the presence of at least one high-
energy shower in the EMCal. After offline calibration it was found that the
ERT-A trigger reached full efficiency for photons with energy above 4.5–5 GeV
depending on location in the calorimeter. The accumulated ERT-A data sample
after the same $|z_{\rm BBC}|<20$ cm vertex cut corresponds to $1.8\times
10^{10}$ sampled MB events, which is a factor of three more than the MB
sample. MB data is used to measure meson yields at $p_{T}<8$ GeV/$c$, and
ERT-A data set is used at higher momenta.

Reconstruction of $\pi^{0}$ and $\eta$ mesons is performed via their decay
modes $\pi^{0}\rightarrow\gamma\gamma$ and $\eta\rightarrow\gamma\gamma$.
Photons are measured in the EMCal Aphecetche  _et al._ (2003) located in the
two central arms of the PHENIX detector, each covering 90 degrees in azimuth
and $|\eta|<0.35$ in pseudorapidity. The EMCal comprises two technologically
different subsystems: lead-scintillator sampling calorimeter (PbSc) and lead-
glass Čerenkov calorimeter (PbGl), which cover $3/8$ and $1/8$ of the full
azimuth, respectively. The PbSc and PbGl subsystems have different linearity,
energy resolution ($\delta E/E=2.1\%\oplus 8.1\%/\sqrt{E}$ for PbSc and
$0.8\%\oplus 5.9\%/\sqrt{E}$ for PbGl) and segmentation
($\delta\phi\times\delta\eta\approx 0.01\times 0.01$ for PbSc and $0.008\times
0.008$ for PbGl).

The raw yields of $\pi^{0}$ and $\eta$ mesons are determined from the
$\gamma\gamma$ invariant mass ($m_{\rm inv}$) distribution, in bins of $p_{T}$
and centrality. The analysis is carried out independently for the PbSc and
PbGl subsystems. Photon candidates have to satisfy a shower shape cut
Aphecetche  _et al._ (2003) and are required to have energy ($E_{\gamma}$)
larger than 0.4 GeV, which helps to further reduce the contribution from other
particles, mostly minimum ionizing hadrons. Each $\gamma\gamma$ pair is
required to satisfy an asymmetry cut $|\alpha|<0.8$, where $\alpha=|E_{\gamma
1}-E_{\gamma 2}|/(E_{\gamma 1}+E_{\gamma 2})$. The asymmetry cut helps to
reduce the background from combinatorial $\gamma\gamma$ pairs in the $m_{\rm
inv}$ distributions, improving the $S/B$ ratio. A typical invariant mass
distribution is shown in Fig. 2.

The $m_{\rm inv}$ distributions contain two peaks in the selected mass region,
which correspond to decays of $\pi^{0}$ and $\eta$. At lower $p_{T}$ the peaks
sit on top of a large combinatorial background. The shape of the background is
estimated by event mixing, i.e. from the $m_{\rm inv}$ distribution obtained
by combining photons from different events that nevertheless have similar
collision vertex and centrality. The mixed event distributions are normalized
and subtracted from the real event distributions. The mixed events are
normalized outside of the meson peaks from $0.080<m_{\rm inv}<0.085$ and
$0.3<m_{\rm inv}<0.4$ GeV/$c^{2}$ for the $\pi^{0}$ and $0.7<m_{\rm inv}<0.8$
GeV/$c$ for the $\eta$. The combinatorial background decreases rapidly with
increasing $p_{T}$, therefore, mixed event subtraction is carried out only for
$p_{T}$ below 7–10 GeV/$c$ depending on the collision centrality. Above that
the background under the peaks is estimated from the average counts in real
events outside, but close to the peaks (sideband).

The resulting, combinatorial-subtracted invariant mass distributions are fit
to a combination of a Gaussian to describe signal and a polynomial to describe
the residual background. First- and second-order polynomials were used in
$\pi^{0}$ and $\eta$ measurements, respectively. Meson raw yields were
obtained as the difference between the integral of the bin content in the mass
peak regions and the integral of the polynomial fits to the residual
background in the same region. The mass peak regions were defined as $m_{\rm
inv}=0.10$-$0.17$ and $0.48$-$0.62$ GeV/$c^{2}$ for $\pi^{0}$ and $\eta$,
respectively.

Acceptance and reconstruction efficiency (efficiency hereafter) are estimated
using a geant3-based Brun  _et al._ (1978) Monte-Carlo simulation of the
PHENIX detector. The simulation was tuned to reproduce the observed mass peaks
and widths of $\pi^{0}$ and $\eta$ in the real data. To account for the effect
of underlying events the simulated mesons were embedded in real data in each
centrality, then analyzed with the same methods as the real data. Final
efficiencies also account for branching ratios of the analyzed decay modes and
for the ERT-A trigger efficiency in the corresponding data sample.

Invariant yields of $\pi^{0}$ and $\eta$ are obtained as follows:

$\frac{1}{N_{\rm event}}\frac{d^{2}N}{2\pi p_{T}dp_{T}dy}=\frac{N_{\rm
raw}}{2\pi p_{T}N_{\rm event}\epsilon_{\rm rec}\Delta p_{T}\Delta y},$ (3)

where $N_{\rm raw}$ is the particle raw yield and $\epsilon_{\rm rec}$ is the
efficiency (including acceptance and all other corrections), $N_{\rm event}$
is the number of analyzed events.

Systematic uncertainties are classified into three types. Type A represents
uncertainties, that are entirely $p_{T}$-uncorrelated; these are added in
quadrature to the statistical uncertainty. Type B uncertainties are
$p_{T}$-correlated, but different from point to point, and all data points can
move up or down by the same fraction of their Type B uncertainty. Type C
represents uncertainties which move all points up or down by the same
fraction. Typical values of the estimated systematic and total uncertainties
are presented in Tables 3 and 3.

Table 2:  Systematic uncertainties for $\pi^{0}$ and $\eta$ yields at different $p_{T}$. Values are shown for PbSc(PbGl) subsystems. The types of uncertainties are described in the text. Values with a range indicate the variation of the uncertainty over the different centrality intervals.  Source | $\pi^{0}\rightarrow\gamma\gamma$ | $\eta\rightarrow\gamma\gamma$ | Type
---|---|---|---
|  $3.25$ GeV/$c$ |  $11$ GeV/$c$ |  $3.25$ GeV/$c$ |  $11$ GeV/$c$ |
Acceptance | 1.5$\%$(1.5$\%$) | 1.5$\%$(1.5$\%$) | 1.5$\%$(1.5$\%$) | 1.5$\%$(1.5$\%$) | B
$p_{T}$ weights | 1$\%$(1$\%$) | 1$\%$(1$\%$) | 1$\%$(1$\%$) | 1$\%$(1$\%$) | B
Energy scale | 5$\%$(5$\%$) | 9$\%$(9$\%$) | 5$\%$(5$\%$) | 9$\%$(9$\%$) | B
Energy resolution | 2$\%$(2$\%$) | 2$\%$(2$\%$) | 2$\%$(2$\%$) | 2$\%$(2$\%$) | B
ERT-A efficiency | $-$ | 1$\%$(1$\%$) | $-$ | 1.3$\%$(1.3$\%$) | B
Photon conversion | 5.2$\%$(5.2$\%$) | 5.2$\%$(5.2$\%$) | 5.2$\%$(5.2$\%$) | 5.2$\%$(5.2$\%$) | C
Cluster merging | $-$ | 3$\%$(2.5$\%$) | $-$ | $-$ | B
PID cuts | 4$\%$(4$\%$)$-$6$\%$(4$\%$) | 4$\%$(4$\%$)$-$6$\%$(4$\%$) | 5$\%$(5$\%$)$-$7$\%$(5$\%$) | 5$\%$(5$\%$)$-$7$\%$(5$\%$) | B
Raw yield extraction | 3$\%$(3$\%$) | 3$\%$(3$\%$)$-$4$\%$(4$\%$) | 8.13$\%$(8.13$\%$) | 5.3$\%$(5.3$\%$) |
Reconstruction efficiency | 0.8$\%$(1.5$\%$)$-$1.7$\%$(3$\%$) | 0.4$\%$(0.7$\%$)$-$0.7$\%$(1.5$\%$) | 3$\%$(5$\%$)$-$4$\%$(8$\%$) | 0.6$\%$(1.2$\%$)$-$1.03$\%$(1.9$\%$) | A

Table 3:  Total uncertainties for $\pi^{0}$ and $\eta$ combined spectra, $R_{AB}$ and $\eta/\pi^{0}$ ratios at different $p_{T}$. The types of uncertainties are described in the text. Values with a range indicate the variation of the uncertainty over different centrality intervals. Type |  $3.25$ GeV/$c$ |  $11$ GeV/$c$ |  $3.25$ GeV/$c$ |  $11$ GeV/$c$
---|---|---|---|---
|  $\pi^{0}$ Combined Spectra |  $\eta$ Combined Spectra
Stat | 0.08$\%-$0.2$\%$ | 0.9$\%-$4$\%$ | 3$\%-$5$\%$ | 4$\%-$11$\%$
Type A | 0.9$\%-$1.8$\%$ | 0.4$\%-$0.9$\%$ | 2$\%-$4$\%$ | 0.6$\%-$0.9$\%$
Type B | 6$\%-$7$\%$ | 10.1$\%-$10.3$\%$ | 8.7$\%-$9.3$\%$ | 10.7$\%-$11.1$\%$
Type C | 5.2$\%$ | 5.2$\%$ | 5.2$\%$ | 5.2$\%$
|  $\pi^{0}$ $R_{AB}$ |  $\eta$ $R_{AB}$
Type A + Stat. | 1.0$\%-$1.9$\%$ | 2.6$\%-$4.4$\%$ | 4$\%-$6$\%$ | 6$\%-$13$\%$
Type B | 10.5$\%-$10.7$\%$ | 14.3$\%-$14.4$\%$ | 13.7$\%-$14.1$\%$ | 14.4$\%-$14.7$\%$
Type C | 12$\%-$23$\%$ | 12$\%-$23$\%$ | 12$\%-$23$\%$ | 12$\%-$23$\%$
| $\eta/\pi^{0}$ |
Type A + Stat. | 4$\%-$6$\%$ | 4$\%-$12$\%$ |  |
Type B | 10.9$\%-$11.4$\%$ | 14.7$\%-$15.1$\%$ |  |
Type C | $-$ | $-$ |  |

Figure 2: Example of an invariant mass plot ($4.5<\mbox{$p_{T}$}<5.0$
GeV/$c$). (a) The foreground (photon pairs from the same event) is shown as
points, the shaded area is the scaled mixed event background. Insert (b) shows
the $\pi^{0}$ peak area after mixed event subtraction; the Gaussian fit to the
peak and the first order polynomial fit to the residual background are also
shown. Insert (c) shows the $\eta$ peak area with the Gaussian fit and second
order polynomial for the residual background.

One of the main sources of systematic uncertainties is the absolute energy
calibration of the EMCal. The uncertainty on the absolute scale was estimated
to be $1\%$. Due to the steeply falling (power-law) spectrum it corresponds to
$\approx 2$-$9\%$ uncertainty for the measured yields of $\pi^{0}$ and $\eta$
mesons, which gradually increases from low to high momentum. At high $p_{T}$
the measured $\pi^{0}$ yields are strongly affected by cluster merging when
two photons from a $\pi^{0}$ decay have a small opening angle and produce
partially or fully overlapping showers, which cannot be reconstructed as two
individual clusters in the EMCal. Cluster merging results in significant loss
of $\pi^{0}$ reconstruction efficiency at high $p_{T}$. Due to the different
segmentation and Moliere-radius Aphecetche  _et al._ (2003) the merging effect
manifests itself differently in the PbSc and PbGl subsystems. In PbSc the
merging starts at $p_{T}>12$ GeV/$c$, while in PbGl it starts only at
$p_{T}>16$ GeV/$c$. Uncertainties on how well the simulations describe the
merging effect result in corresponding uncertainties for the measured
$\pi^{0}$ yields, increase with $p_{T}$, reaching $\approx$20$\%$ in PbSc and
$\approx$9$\%$ in PbGl at 20 GeV/$c$. Due to the four times heavier mass and
larger $\gamma\gamma$ opening angle, the $\eta$ measurements will be
influenced by cluster merging only at $p_{T}>50$ GeV/$c$, which is far beyond
the $p_{T}$ range presented in this analysis. At low $p_{T}$ (below $\approx$5
GeV/$c$) the main uncertainty for $\pi^{0}$ and $\eta$ comes from the raw
yield extraction due to relatively small $S/B$ ratios. This uncertainty is
estimated as the maximum difference between raw yields obtained using
different mass regions for mixed event background normalization, different
fitting ranges, and different order polynomials for the residual background
estimation. Some photons from $\pi^{0}$ and $\eta$ decays convert into
$e^{-}e^{+}$ pairs when traversing through detector material. If this happens
within the magnetic field, they are bent in opposite directions and can not be
reconstructed as a single photon-like cluster in the EMCal. As a result,
$\approx 25\%$ of $\pi^{0}$ and $\eta$ mesons are lost. This effect is
included in the efficiency calculation. The uncertainty on how accurately it
is reproduced in the simulation is estimated to be $5.2\%$, and it is Type-C,
because in the relevant energy range the conversion probability is almost
constant.

Systematic uncertainties for $\eta/\pi^{0}$ ratios are included as a quadratic
sum of the type-B uncertainties from $\pi^{0}$ and $\eta$ yields. Because
type-C uncertainties of the $\pi^{0}$ and $\eta$ yields are 100% correlated
between these particle measurements for all $p_{T}$, this uncertainty cancels
in the ratios. The $p_{T}$-correlated systematic uncertainties for $R_{AB}$
include both uncertainties from Cu$+$Au and $p$+$p$ measurements Adare  _et
al._ (2007).

Invariant yields are obtained separately for PbSc and PbGl subsystems. The
results are then averaged with weights defined by the quadratic sum of
statistical and those systematic uncertainties that are uncorrelated between
the two subsystems. The ratios of the yields obtained in PbSc and PbGl to the
averaged ones are presented in panels (b)-(d) and (f)-(h) of Fig. 3. Only
uncorrelated systematic uncertainties are shown in the ratios. Yields obtained
in the different subsystems are consistent within statistical and uncorrelated
systematic uncertainties. Typical systematic uncertainties for the combined
spectra, $\pi^{0}$ and $\eta$ $R_{AB}$ and $\eta$/$\pi^{0}$ ratio are listed
in Table 3.

To facilitate comparison between different experiments and data sets, the data
points of the meson spectra are plotted at the center of each given $p_{T}$
interval, which, due to the falling spectrum, does not represent the true
physical value of the yield at that $p_{T}$ Lafferty and Wyatt (1995). A bin-
shift correction is applied that adjusts the meson yields to their value at
the bin center.

Figure 3: Left: $\pi^{0}$ (a) and $\eta$ (e) invariant $p_{T}$-spectra
measured in different centrality intervals of Cu$+$Au collisions at
$\sqrt{s_{{}_{NN}}}$=200 GeV. The dashed curves are a fit with two Hagedorn-
type functions with an asymptotic power-law ($\mbox{$p_{T}$}^{-n}$) behavior.
Right: ratios of $\pi^{0}$ (b-d) and $\eta$ (f-h) yields measured in PbSc or
PbGl subsystem to the averaged ones. Error bars represent a quadratic sum of
statistical and type-A systematic uncertainties. Error boxes in the right
panel correspond to the quadratic sum of systematic uncertainties, which are
uncorrelated between PbSc and PbGl.  Figure 4:  Ratios of $\eta$ and $\pi^{0}$
yields measured as a function of $p_{T}$ in different centrality intervals of
Cu$+$Au collisions at $\sqrt{s_{{}_{NN}}}$=200 GeV. Dashed curve shows the
$m_{T}$ scaling curve normalized to 0.5 at high momentum (see text). Error
bars represent a quadratic sum of statistical and type-A systematic
uncertainties for $\pi^{0}$ and $\eta$ yields. Error boxes represent a
quadratic sum of type-B systematic uncertainties for $\pi^{0}$ and $\eta$
yields.

Figure 5:  $R_{AB}$ of $\pi^{0}$ and $\eta$ mesons measured as a function of
$p_{T}$ in different centrality intervals of Cu$+$Au collisions at
$\sqrt{s_{{}_{NN}}}$=200 GeV. Error bars represent a quadratic sum of
statistical and type-A systematic uncertainties from Cu$+$Au and $p$+$p$
measurements, respectively. Error boxes represent type-B systematic
uncertainties from Cu$+$Au and $p$+$p$ measurements. Solid and open boxes at
unity represent type-C systematic uncertainties from Cu$+$Au (including
uncertainties from the $T_{AB}$ values) and $p$+$p$, respectively. The
reference $p$+$p$ measurements are published in Adare  _et al._ (2007) for
$\pi^{0}$ and in Adare  _et al._ (2011, 2010) for $\eta$ (see details in the
text).

Figure 6: Comparison of $\pi^{0}$ $R_{AB}$ measured in Cu$+$Au, Au$+$Au and
Cu$+$Cu collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV and comparable $N_{\rm
part}$. Error bars represent a quadratic sum of statistical and type-A
systematic uncertainties from Cu$+$Au and $p$$+$$p$ measurements. Open boxes
are Type-B systematic uncertainties for Cu$+$Au and $p$$+$$p$ collisions. The
three boxes at unity are type-C systematic uncertainties from $p$$+$$p$ and
heavy-ion collisions. The boxes from left to right correspond to Cu$+$Au,
Au$+$Au and Cu$+$Cu measurements, respectively.

Figure 7:  Comparison of integrated $R_{AB}$ for $\pi^{0}$ measured as a
function of $N_{\rm part}$ in Cu$+$Au and Au$+$Au collisions at
$\sqrt{s_{{}_{NN}}}=200$ GeV. Uncertainties are the same as in the Fig. 7. The
lower limit of integration is $p_{T}$ =5 GeV/$c$ on panel (a), $p_{T}$ =10
GeV/$c$ on panel (b).

##  III Results and discussion

Invariant yields in the $p_{T}$ range 1(2)-20 GeV/$c$ for $\pi^{0}$ ($\eta$)
mesons measured in different centrality intervals and MB collisions are shown
in panels (a) and (e) of Fig. 3, respectively. At low $p_{T}$ the measurement
is limited by the rapidly decreasing $S/B$ ratio, and at high $p_{T}$ by the
available statistics.

Spectra of $\pi^{0}$ and $\eta$ mesons can be fitted with a sum of Hagedorn
and power-law functions:

$f(p_{T})=T(p_{T})\frac{A}{(1+p_{T}/p_{0})^{m}}+(1-T(p_{T}))\frac{B}{p^{n}_{T}},$
(4)

where $T(p_{T})=1/(1+\exp((p_{T}-t)/w))$, $A$, $p_{0}$, $m$, $B$, $n$, $t$ and
$w$ are free parameters. The parameter $t$ governs at what $p_{T}$ the second,
pure power-law term becomes dominant; $t$ varies between 4–6 GeV/$c$,
depending on centrality. The parameter $w$ varies between 0.05–0.15 GeV/$c$
and governs the width of transition interval, where the first term loses its
dominance and the second term becomes dominant. At high transverse momenta
$f(p_{T})\propto\mbox{$p_{T}$}^{-n}$. For $\pi^{0}$ in MB collisions
$n=8.06\pm 0.01_{\rm stat}\pm 0.06_{\rm sys}$, for the most central 0%–10%
collisions $n=8.02\pm 0.02_{\rm stat}\pm 0.07_{\rm sys}$, and increases slowly
to $n=8.07\pm 0.02_{\rm stat}\pm 0.06_{\rm sys}$ up to 40% centrality. These
numbers are consistent within uncertainties to the values obtained in pure
power-law fits at high $p_{T}$ ($>$8 GeV/$c$) in 200 GeV Au$+$Au collisions
with similar $N_{\rm part}$ Adare  _et al._ (2008b, 2013).

The $\eta/\pi^{0}$ ratios ($R_{\eta/\pi^{0}}$) as a function of $p_{T}$ for
different Cu$+$Au centrality intervals are presented in the Fig. 4. Within
uncertainties the measured $R_{\eta/\pi^{0}}$ are centrality independent in
the whole $p_{T}$ range of measurements. A constant fit to the MB data in the
4$<\mbox{$p_{T}$}<$20 GeV/$c$ region results in $\eta/\mbox{$\pi^{0}$}=0.50\pm
0.01_{\rm stat}\pm 0.02_{\rm sys}$, and the various centrality bins are
consistent with this value. The dashed curve in Fig. 4 shows this
asymptotically constant fit modified according to $m_{T}$-scaling. Similar
results were obtained in hadron-hadron, hadron-nucleus, and nucleus-nucleus
collisions as well as in $e^{+}e^{-}$ collisions in a wide range of collision
energies $\sqrt{s_{{}_{NN}}}=3$–1800 GeV Busser  _et al._ (1975); Adler  _et
al._ (2007). This suggests that QGP medium produced in Cu$+$Au collisions
either does not affect the jet fragmentation into light mesons or it affects
the $\pi^{0}$ and $\eta$ the same way.

Nuclear modification factors of $\pi^{0}$ and $\eta$ mesons as functions of
$p_{T}$ are shown in Fig. 5 for different Cu$+$Au centrality intervals. The
reference $\pi^{0}$ meson production cross section in $p$+$p$ collisions was
obtained from the 2005 PHENIX $p$+$p$ measurement Adare  _et al._ (2007). For
$\eta$ meson $R_{AB}$ estimation, the 2006 PHENIX $p$+$p$ measurements were
used Adare  _et al._ (2011). The $R_{AB}$-s of $\pi^{0}$ and $\eta$ mesons are
consistent within uncertainties in the whole $p_{T}$ range for every analyzed
centrality interval of Cu$+$Au collisions. At $p_{T}>5$ GeV/$c$ $R_{AB}$ is
$\approx 0.4-0.5$ in most central collisions. A weak $p_{T}$ dependence of the
measured $R_{AB}$ values can be observed. The suppression of $\pi^{0}$ and
$\eta$ decreases as one moves to more peripheral collisions.

Fig. 7 compares $R_{AB}$ of $\pi^{0}$ mesons measured as a function of $p_{T}$
in Cu$+$Au, Au$+$Au Adare  _et al._ (2008b) and Cu$+$Cu Adare  _et al._
(2008c) collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV and similar $N_{\rm part}$.
In central and semi-central Cu$+$Au collisions $\pi^{0}$ $R_{AB}$ are
consistent with those measured in Au$+$Au and Cu$+$Cu, if applicable, which
suggests that $\pi^{0}$ suppression mostly depends on the energy density and
size of the produced medium. Because in the most central collisions the Cu ion
is fully submerged in Au, without any ”corona” Pantuev (2007), but the
suppression is the same as in Au$+$Au at comparable $N_{\rm part}$, the
corona-effect is either nonexistent or very small.

In Fig. 7, the $\pi^{0}$ and $\eta$ integrated $R_{AB}$’s are shown as a
function of $N_{\rm part}$ and compared to Au$+$Au. The integration is carried
out in two different $p_{T}$ ranges ($\mbox{$p_{T}$}>5$ GeV/$c$ and
$\mbox{$p_{T}$}>10$ GeV/$c$). The results obtained for the two different
collision systems are consistent within uncertainties.

##  IV Summary

In summary, PHENIX has measured $\pi^{0}$ and $\eta$ invariant $p_{T}$-spectra
and nuclear modification factors in asymmetric collisions of heavy ions,
Cu$+$Au at $\sqrt{s_{{}_{NN}}}=200$ GeV in a wide $p_{T}$ range
($1(2)<p_{T}<20$ GeV/$c$) and for several centrality intervals. In the more
central collisions the spectra are similar to those observed in Au$+$Au. The
asymptotic (high $p_{T}$) value of $\eta/\mbox{$\pi^{0}$}$ is $0.50\pm
0.01_{\rm stat}\pm 0.02_{\rm sys}$, constant, independent of collision
centrality, and consistent with the previously measured values in hadron-
hadron, hadron-nucleus, nucleus-nucleus as well as $e^{+}e^{-}$ collisions at
$\sqrt{s_{{}_{NN}}}=$3–1800 GeV, suggesting that either the fragmentation of
jets into $\pi^{0}$ and $\eta$ is unchanged irrespective of the absence or
presence of the medium, or it changes the same way, despite the different
flavor content. The values of $R_{AB}$ for $\pi^{0}$ and $\eta$ are consistent
within uncertainties in all analyzed centrality intervals of Cu$+$Au
collisions. The suppression pattern of $\pi^{0}$ in Cu$+$Au collisions is
consistent with Au$+$Au and Cu$+$Cu collisions at the same interaction energy
and similar values of $N_{\rm part}$.

###### 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, 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), Croatian Science
Foundation and Ministry of Science and Education (Croatia), 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), Bundesministerium
für Bildung und Forschung, Deutscher Akademischer Austausch Dienst, and
Alexander von Humboldt Stiftung (Germany), J. Bolyai Research Scholarship,
EFOP, the New National Excellence Program (ÚNKP), NKFIH, and OTKA (Hungary),
Department of Atomic Energy and Department of Science and Technology (India),
Israel Science Foundation (Israel), Basic Science Research Program through NRF
of the Ministry of Education (Korea), Physics Department, Lahore University of
Management Sciences (Pakistan), Ministry of Education and Science, Russian
Academy of Sciences, Federal Agency of Atomic Energy (Russia), VR and
Wallenberg Foundation (Sweden), the U.S. Civilian Research and Development
Foundation for the Independent States of the Former Soviet Union, the
Hungarian American Enterprise Scholarship Fund, the US-Hungarian Fulbright
Foundation, and the US-Israel Binational Science Foundation.

## References

  * Arsene  _et al._ (2005) I. Arsene _et al._ (BRAHMS Collaboration), “Quark gluon plasma and color glass condensate at RHIC? The Perspective from the BRAHMS experiment,” Nucl. Phys. A 757, 1 (2005).
  * Back  _et al._ (2005) B. B. Back _et al._ , “The PHOBOS perspective on discoveries at RHIC,” Nucl. Phys. A 757, 28 (2005).
  * Adams  _et al._ (2005) J. Adams _et al._ (STAR Collaboration), “Experimental and theoretical challenges in the search for the quark gluon plasma: The STAR Collaboration’s critical assessment of the evidence from RHIC collisions,” Nucl. Phys. A 757, 102 (2005).
  * Adcox  _et al._ (2005) K. Adcox _et al._ (PHENIX Collaboration), “Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration,” Nucl. Phys. A 757, 184 (2005).
  * Chatrchyan  _et al._ (2012) S. Chatrchyan _et al._ (CMS Collaboration), “Study of high-pT charged particle suppression in PbPb compared to $pp$ collisions at $\sqrt{s_{NN}}=2.76$ TeV,” Eur. Phys. J. C 72, 1945 (2012).
  * Abelev  _et al._ (2013) B. Abelev _et al._ (ALICE Collaboration), “Centrality Dependence of Charged Particle Production at Large Transverse Momentum in Pb–Pb Collisions at $\sqrt{s_{NN}}=2.76$ TeV,” Phys. Lett. B 720, 52 (2013).
  * Aad  _et al._ (2013) G. Aad _et al._ (ATLAS Collaboration), “Measurement of the jet radius and transverse momentum dependence of inclusive jet suppression in lead-lead collisions at $\sqrt{s_{NN}}$= 2.76 TeV with the ATLAS detector,” Phys. Lett. B 719, 220 (2013).
  * Gunji (2016) T. Gunji (ALICE Collaboration), “Overview of recent ALICE results,”  _Proceedings, 25th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2015): Kobe, Japan, September 27-October 3, 2015_ , Nucl. Phys. A 956, 11 (2016).
  * Jacob and Landshoff (1978) M. Jacob and P. V Landshoff, “Large transverse momentum and jet studies,” Physics Reports 48, 285–350 (1978).
  * Baier  _et al._ (2000) R. Baier, D. Schiff, and B. G. Zakharov, “Energy loss in perturbative QCD,” Ann. Rev. Nucl. Part. Sci. 50, 37 (2000).
  * Owens (1987) J. F. Owens, “Large Momentum Transfer Production of Direct Photons, Jets, and Particles,” Rev. Mod. Phys. 59, 465 (1987).
  * Adare  _et al._ (2007) A. Adare _et al._ (PHENIX Collaboration), “Inclusive cross-section and double helicity asymmetry for $\pi^{0}$ production in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV: Implications for the polarized gluon distribution in the proton,” Phys. Rev. D 76, 051106 (2007).
  * (13) I. Helenius, K. J. Eskola, H. Honkanen, and C. A. Salgado, “Impact-Parameter Dependent Nuclear Parton Distribution Functions: EPS09s and EKS98s and Their Applications in Nuclear Hard Processes,” J. High Energy Phys. 07 (2012) 073\.
  * Eskola  _et al._ (2017) K. J. Eskola, P. Paakkinen, H. Paukkunen, and Carlos A. Salgado, “EPPS16: Nuclear parton distributions with LHC data,” Eur. Phys. J. C 77, 163 (2017).
  * Bjorken (1982) J. D. Bjorken, “Energy Loss of Energetic Partons in Quark - Gluon Plasma: Possible Extinction of High p(t) Jets in Hadron - Hadron Collisions,” (1982), FERMILAB-PUB-82-059-THY, FERMILAB-PUB-82-059-T.
  * Wang  _et al._ (1995) X.-N. Wang, M. Gyulassy, and M. Plumer, “The LPM effect in QCD and radiative energy loss in a quark gluon plasma,” Phys. Rev. D 51, 3436 (1995).
  * Majumder  _et al._ (2007) A. Majumder, B. Müller, and X.-N. Wang, “Small shear viscosity of a quark-gluon plasma implies strong jet quenching,” Phys. Rev. Lett. 99, 192301 (2007).
  * Qin  _et al._ (2008) G.-Y. Qin, J. Ruppert, C. Gale, S. Jeon, G. D. Moore, and M. G. Mustafa, “Radiative and collisional jet energy loss in the quark-gluon plasma at RHIC,” Phys. Rev. Lett. 100, 072301 (2008).
  * Chen  _et al._ (2011) X.-F. Chen, T. Hirano, E. Wang, X.-N. Wang, and H. Zhang, “Suppression of high-${p}_{T}$ hadrons in Pb+Pb collisions at energies available at the CERN-Large Hadron Collider,” Phys. Rev. C 84, 034902 (2011).
  * Young  _et al._ (2012) C. Young, B. Schenke, S. Jeon, and C. Gale, “MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization,” Physical Review C 86, 034905 (2012).
  * Majumder and Shen (2012) A Majumder and C Shen, “Suppression of the High-${p}_{T}$ Charged-Hadron ${R}_{AA}$ at the LHC,” Phys. Rev. Lett. 109, 202301 (2012).
  * Xu  _et al._ (2014) J. Xu, A. Buzatti, and M. Gyulassy, “Azimuthal jet flavor tomography with CUJET2.0 of nuclear collisions at RHIC and LHC,” JHEP 08, 63 (2014).
  * Majumder (2013) A. Majumder, “Calculating the jet quenching parameter $\hat{q}$ in lattice gauge theory,” Phys. Rev. C 87, 034905 (2013).
  * Panero  _et al._ (2014) M. Panero, K. Rummukainen, and A. Schäfer, “Lattice Study of the Jet Quenching Parameter,” Phys. Rev. Lett. 112, 162001 (2014).
  * Miller  _et al._ (2007) M. L. Miller, K. Reygers, S. J. Sanders, and P. Steinberg, “Glauber modeling in high energy nuclear collisions,” Ann. Rev. Nucl. Part. Sci. 57, 205 (2007).
  * Adler  _et al._ (2007) S. S. Adler _et al._ (PHENIX Collaboration), “High transverse momentum $\eta$ meson production in $p$$+$$p$, $d$$+$Au and Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV,” Phys. Rev. C 75, 024909 (2007).
  * Adare  _et al._ (2008a) A. Adare _et al._ (PHENIX Collaboration), “Quantitative Constraints on the Opacity of Hot Partonic Matter from Semi-Inclusive Single High Transverse Momentum Pion Suppression in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV,” Phys. Rev. C 77, 064907 (2008a).
  * Adare  _et al._ (2008b) A. Adare _et al._ (PHENIX Collaboration), “Suppression pattern of neutral pions at high transverse momentum in Au + Au collisions at $\sqrt{s_{NN}}$ = 200-GeV and constraints on medium transport coefficients,” Phys. Rev. Lett. 101, 232301 (2008b).
  * Adare  _et al._ (2008c) A. Adare _et al._ (PHENIX Collaboration), “Onset of $\pi^{0}$ Suppression Studied in Cu+Cu Collisions at $\sqrt{s_{NN}}=22.4$, 62.4, and 200 GeV,” Phys. Rev. Lett. 101, 162301 (2008c).
  * Adare  _et al._ (2010) A. Adare _et al._ (PHENIX Collaboration), “Transverse momentum dependence of $\eta$ meson suppression in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV,” Phys. Rev. C 82, 011902 (2010).
  * Pantuev (2007) V. S. Pantuev, “Jet absorption and corona effect at RHIC: Extracting collision geometry from experimental data,” JETP Lett. 85, 104 (2007).
  * Adcox  _et al._ (2003) K. Adcox _et al._ (PHENIX Collaboration), “PHENIX detector overview,” Nucl. Instrum. Methods Phys. Res., Sec. A 499, 469 (2003).
  * Allen  _et al._ (2003) M. Allen _et al._ (PHENIX Collaboration), “PHENIX inner detectors,” Nucl. Instrum. Methods Phys. Res., Sec. A 499, 549 (2003).
  * Adler  _et al._ (2003) S. S. Adler _et al._ (PHENIX Collaboration), “PHENIX on-line systems,” Nucl. Instrum. Methods Phys. Res., Sec. A 499, 560 (2003).
  * Aphecetche  _et al._ (2003) L. Aphecetche _et al._ (PHENIX Collaboration), “PHENIX calorimeter,” Nucl. Instrum. Methods Phys. Res., Sec. A 499, 521 (2003).
  * Brun  _et al._ (1978) R. Brun, R. Hagelberg, M. Hansroul, and J. C. Lassalle, “GEANT: Simulation Program for Particle Physics Experiments. User Guide and Reference Manual,” (1978), CERN-DD-78-2-REV.
  * Lafferty and Wyatt (1995) G. D. Lafferty and T. R. Wyatt, “Where to stick your data points: The treatment of measurements within wide bins,” Nucl. Instrum. Methods Phys. Res., Sec. A 355, 541 (1995).
  * Adare  _et al._ (2011) A. Adare _et al._ (PHENIX Collaboration), “Cross section and double helicity asymmetry for $\eta$ mesons and their comparison to neutral pion production in $p$+$p$ collisions at $\sqrt{s}=200GeV$,” Phys. Rev. D 83, 032001 (2011).
  * Adare  _et al._ (2013) A. Adare _et al._ (PHENIX Collaboration), “Neutral pion production with respect to centrality and reaction plane in Au$+$Au collisions at $\sqrt{s_{NN}}$=200 GeV,” Phys. Rev. C 87, 034911 (2013).
  * Busser  _et al._ (1975) F. W. Busser _et al._ , “A Study of High Transverse Momentum eta and pi0 Mesons at the CERN ISR,” Phys. Lett. B 55, 232 (1975).