Phys. Rev. D
76,
051106(R)
(2007)
[7 pages]
Inclusive cross section and double helicity asymmetry for π0 production in p+p collisions at √s=200 GeV: Implications for the polarized gluon distribution in the proton
A. Adare et al. PHENIX Collaboration
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A. Adare8, S. Afanasiev22, C. Aidala9, N. N. Ajitanand48, Y. Akiba42,43, H. Al-Bataineh37, J. Alexander48, K. Aoki27,42, L. Aphecetche50, R. Armendariz37, S. H. Aronson3, J. Asai43, E. T. Atomssa28, R. Averbeck49, T. C. Awes38, B. Azmoun3, V. Babintsev18, G. Baksay14, L. Baksay14, A. Baldisseri11, K. N. Barish4, P. D. Barnes30, B. Bassalleck36, S. Bathe4, S. Batsouli38, V. Baublis41, A. Bazilevsky3, S. Belikov3, R. Bennett49, Y. Berdnikov45, A. A. Bickley8, J. G. Boissevain30, H. Borel11, K. Boyle49, M. L. Brooks30, H. Buesching3, V. Bumazhnov18, G. Bunce3,43, S. Butsyk30,49, S. Campbell49, B. S. Chang57, J.-L. Charvet11, S. Chernichenko18, J. Chiba23, C. Y. Chi9, M. Chiu19, I. J. Choi57, T. Chujo54, P. Chung48, A. Churyn18, V. Cianciolo38, C. R. Cleven16, B. A. Cole9, M. P. Comets39, P. Constantin30, M. Csanád13, T. Csörgő24, T. Dahms49, K. Das15, G. David3, M. B. Deaton1, K. Dehmelt14, H. Delagrange50, A. Denisov18, D. d’Enterria9, A. Deshpande43,49, E. J. Desmond3, O. Dietzsch46, A. Dion49, M. Donadelli46, O. Drapier28, A. Drees49, A. K. Dubey56, A. Durum18, V. Dzhordzhadze4, Y. V. Efremenko38, J. Egdemir49, F. Ellinghaus8, W. S. Emam4, A. Enokizono29, H. En’yo42,43, S. Esumi53, K. O. Eyser4, D. E. Fields36,43, M. Finger5,22, M. Finger, Jr.5,22, F. Fleuret28, S. L. Fokin26, Z. Fraenkel56, J. E. Frantz49, A. Franz3, A. D. Frawley15, K. Fujiwara42, Y. Fukao27,42, T. Fusayasu35, S. Gadrat31, I. Garishvili51, A. Glenn8, H. Gong49, M. Gonin28, J. Gosset11, Y. Goto42,43, R. Granier de Cassagnac28, N. Grau21, S. V. Greene54, M. Grosse Perdekamp19,43, T. Gunji7, H.-Å. Gustafsson32, T. Hachiya17, A. Hadj Henni50, C. Haegemann36, J. S. Haggerty3, H. Hamagaki7, R. Han40, H. Harada17, E. P. Hartouni29, K. Haruna17, E. Haslum32, R. Hayano7, M. Heffner29, T. K. Hemmick49, T. Hester4, X. He16, H. Hiejima19, J. C. Hill21, R. Hobbs36, M. Hohlmann14, W. Holzmann48, K. Homma17, B. Hong25, T. Horaguchi42,52, D. Hornback51, T. Ichihara42,43, K. Imai27,42, M. Inaba53, Y. Inoue44,42, D. Isenhower1, L. Isenhower1, M. Ishihara42, T. Isobe7, M. Issah48, A. Isupov22, B. V. Jacak49,*, J. Jia9, J. Jin9, O. Jinnouchi43, B. M. Johnson3, K. S. Joo34, D. Jouan39, F. Kajihara7, S. Kametani7,55, N. Kamihara42, J. Kamin49, M. Kaneta43, J. H. Kang57, H. Kanou42,52, D. Kawall43, A. V. Kazantsev26, A. Khanzadeev41, J. Kikuchi55, D. H. Kim34, D. J. Kim57, E. Kim47, E. Kinney8, A. Kiss13, E. Kistenev3, A. Kiyomichi42, J. Klay29, C. Klein-Boesing33, L. Kochenda41, V. Kochetkov18, B. Komkov41, M. Konno53, D. Kotchetkov4, A. Kozlov56, A. Král10, A. Kravitz9, J. Kubart5,20, G. J. Kunde30, N. Kurihara7, K. Kurita44,42, M. J. Kweon25, Y. Kwon51,57, G. S. Kyle37, R. Lacey48, Y.-S. Lai9, J. G. Lajoie21, A. Lebedev21, D. M. Lee30, M. K. Lee57, T. Lee47, M. J. Leitch30, M. A. L. Leite46, B. Lenzi46, T. Liška10, A. Litvinenko22, M. X. Liu30, X. Li6, B. Love54, D. Lynch3, C. F. Maguire54, Y. I. Makdisi3, A. Malakhov22, M. D. Malik36, V. I. Manko26, Y. Mao40,42, L. Mašek5,20, H. Masui53, F. Matathias9, M. McCumber49, P. L. McGaughey30, Y. Miake53, P. Mikeš5,20, K. Miki53, T. E. Miller54, A. Milov49, S. Mioduszewski3, M. Mishra2, J. T. Mitchell3, M. Mitrovski48, A. Morreale4, D. P. Morrison3, T. V. Moukhanova26, D. Mukhopadhyay54, J. Murata44,42, S. Nagamiya23, Y. Nagata53, J. L. Nagle8, M. Naglis56, I. Nakagawa42,43, Y. Nakamiya17, T. Nakamura17, K. Nakano42,52, J. Newby29, M. Nguyen49, B. E. Norman30, A. S. Nyanin26, E. O’Brien3, S. X. Oda7, C. A. Ogilvie21, H. Ohnishi42, H. Okada27,42, K. Okada43, M. Oka53, O. O. Omiwade1, A. Oskarsson32, M. Ouchida17, K. Ozawa7, R. Pak3, D. Pal54, A. P. T. Palounek30, V. Pantuev49, V. Papavassiliou37, J. Park47, W. J. Park25, S. F. Pate37, H. Pei21, J.-C. Peng19, H. Pereira11, V. Peresedov22, D. Yu. Peressounko26, C. Pinkenburg3, M. L. Purschke3, A. K. Purwar30, H. Qu16, J. Rak36, A. Rakotozafindrabe28, I. Ravinovich56, K. F. Read38,51, S. Rembeczki14, M. Reuter49, K. Reygers33, V. Riabov41, Y. Riabov41, G. Roche31, A. Romana28,†, M. Rosati21, S. S. E. Rosendahl32, P. Rosnet31, P. Rukoyatkin22, V. L. Rykov42, B. Sahlmueller33, N. Saito27,42,43, T. Sakaguchi3, S. Sakai53, H. Sakata17, V. Samsonov41, S. Sato23, S. Sawada23, J. Seele8, R. Seidl19, V. Semenov18, R. Seto4, D. Sharma56, I. Shein18, A. Shevel41,48, T.-A. Shibata42,52, K. Shigaki17, M. Shimomura53, K. Shoji27,42, A. Sickles49, C. L. Silva46, D. Silvermyr38, C. Silvestre11, K. S. Sim25, C. P. Singh2, V. Singh2, S. Skutnik21, M. Slunečka5,22, A. Soldatov18, R. A. Soltz29, W. E. Sondheim30, S. P. Sorensen51, I. V. Sourikova3, F. Staley11, P. W. Stankus38, E. Stenlund32, M. Stepanov37, A. Ster24, S. P. Stoll3, T. Sugitate17, C. Suire39, J. Sziklai24, T. Tabaru43, S. Takagi53, E. M. Takagui46, A. Taketani42,43, Y. Tanaka35, K. Tanida42,43, M. J. Tannenbaum3, A. Taranenko48, P. Tarján12, T. L. Thomas36, M. Togawa27,42, A. Toia49, J. Tojo42, L. Tomášek20, H. Torii42, R. S. Towell1, V-N. Tram28, I. Tserruya56, Y. Tsuchimoto17, C. Vale21, H. Valle54, H. W. van Hecke30, J. Velkovska54, R. Vertesi12, A. A. Vinogradov26, M. Virius10, V. Vrba20, E. Vznuzdaev41, M. Wagner27,42, D. Walker49, X. R. Wang37, Y. Watanabe42,43, J. Wessels33, S. N. White3, D. Winter9, C. L. Woody3, M. Wysocki8, W. Xie43, Y. Yamaguchi55, A. Yanovich18, Z. Yasin4, J. Ying16, S. Yokkaichi42,43, G. R. Young38, I. Younus36, I. E. Yushmanov26, W. A. Zajc9, O. Zaudtke33, C. Zhang38, S. Zhou6, J. Zimányi24,†, and L. Zolin22 (PHENIX Collaboration)
1Abilene Christian University, Abilene, Texas 79699, USA
2Department of Physics, Banaras Hindu University, Varanasi 221005, India
3Brookhaven National Laboratory, Upton, New York 11973-5000, USA
4University of California, Riverside, Riverside, California 92521, USA
5Charles University, Ovocný trh 5, Praha 1, 116 36 Prague, Czech Republic
6China Institute of Atomic Energy (CIAE), Beijing, People’s Republic of China
7Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
8University of Colorado, Boulder, Colorado 80309, USA
9Columbia University, New York, New York 10027, USA, and Nevis Laboratories, Irvington, New York 10533, USA
10Czech Technical University, Zikova 4, Praha 6, 166 36 Prague, Czech Republic
11Dapnia, CEA Saclay, F-91191 Gif-sur-Yvette, France
12Debrecen University, H-4010 Debrecen, Egyetem tér 1, Hungary
13ELTE, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/A, Hungary
14Florida Institute of Technology, Melbourne, Florida 32901, USA
15Florida State University, Tallahassee, Florida 32306, USA
16Georgia State University, Atlanta, Georgia 30303, USA
17Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan
18IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino 142281, Russia
19University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
20Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, Praha 8, 182 21 Prague, Czech Republic
21Iowa State University, Ames, Iowa 50011, USA
22Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia
23KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
24KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, P.O. Box 49, Budapest, Hungary
25Korea University, Seoul, 136-701, Korea
26Russian Research Center Kurchatov Institute, Moscow, Russia
27Kyoto University, Kyoto 606-8502, Japan
28Laboratoire Leprince-Ringuet, Ecole Polytechnique (CNRS-IN2P3), Route de Saclay, F-91128 Palaiseau, France
29Lawrence Livermore National Laboratory, Livermore, California 94550, USA
30Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
31LPC, Université Blaise Pascal (CNRS-IN2P3), Clermont-Fd, 63177 Aubiere Cedex, France
32Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
33Institut für Kernphysik, University of Muenster, D-48149 Muenster, Germany
34Myongji University, Yongin, Kyonggido 449-728, Korea
35Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, Japan
36University of New Mexico, Albuquerque, New Mexico 87131, USA
37New Mexico State University, Las Cruces, New Mexico 88003, USA
38Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
39IPN-Orsay, Université Paris Sud (CNRS-IN2P3), BP 1, F-91406 Orsay, France
40Peking University, Beijing, People’s Republic of China
41Petersburg Nuclear Physics Institute (PNPI), Gatchina, Leningrad Region 188300, Russia
42RIKEN, The Institute of Physical and Chemical Research, Wako, Saitama 351-0198, Japan
43RIKEN BNL Research Center, Brookhaven National Laboratory, , Upton, New York 11973-5000, USA
44Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan
45Saint Petersburg State Polytechnic University, St. Petersburg, Russia
46Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, Brazil
47System Electronics Laboratory, Seoul National University, Seoul, South Korea
48Chemistry Department, Stony Brook University, SUNY, Stony Brook, New York 11794-3400, USA
49Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
50SUBATECH Ecole des Mines de Nantes (CNRS-IN2P3), Université de Nantes BP 20722 - 44307 Nantes, France
51University of Tennessee, Knoxville, Tennessee 37996, USA
52Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan
53Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan
54Vanderbilt University, Nashville, Tennessee 37235, USA
55Waseda University, Advanced Research Institute for Science and Engineering, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan
56Weizmann Institute, Rehovot 76100, Israel
57Yonsei University, IPAP, Seoul 120-749, Korea
Received 27 April 2007; published 25 September 2007
The PHENIX experiment presents results from the Relativistic Heavy Ion Collider 2005 run with polarized proton collisions at √s=200 GeV, for inclusive π0 production at midrapidity. Unpolarized cross section results are given for transverse momenta pT=0.5 to 20 GeV/c, extending the range of published data to both lower and higher pT. The cross section is described well for pT<1 GeV/c by an exponential in pT, and, for pT>2 GeV/c, by perturbative QCD. Double helicity asymmetries ALL are presented based on a factor of 5 improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton. Using one representative model of gluon polarization it is demonstrated that the gluon spin contribution to the proton spin is significantly constrained.
© 2007 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevD.76.051106
DOI:
10.1103/PhysRevD.76.051106
PACS:
13.85.Ni, 13.88.+e, 21.10.Hw, 25.40.Ep
*PHENIX spokesperson: jacak@skipper.physics.sunysb.edu †Deceased
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