Detailed measurement of the e(+)e(-) pair continuum in p plus p and Au plus Au collisions at root s(NN)=200 GeV and implications for direct photon production

A. Adare, S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, H. Al-Bataineh, J. Alexander, A. Al-Jamel, K. Aoki, L. Aphecetche, R. Armendariz, S. H. Aronson, J. Asai, E. T. Atomssa, R. Averbeck, T. C. Awes, B. Azmoun, V. Babintsev, G. Baksay, L. BaksayA. Baldisseri, K. N. Barish, P. D. Barnes, B. Bassalleck, S. Bathe, S. Batsouli, V. Baublis, F. Bauer, A. Bazilevsky, S. Belikov, R. Bennett, Y. Berdnikov, A. A. Bickley, M. T. Bjorndal, J. G. Boissevain, H. Borel, K. Boyle, M. L. Brooks, D. S. Brown, D. Bucher, H. Buesching, V. Bumazhnov, G. Bunce, J. M. Burward-Hoy, S. Butsyk, S. Campbell, J-S. Chai, B. S. Chang, J-L. Charvet, S. Chernichenko, J. Chiba, C. Y. Chi, M. Chiu, I. J. Choi, T. Chujo, P. Chung, A. Churyn, V. Cianciolo, C. R. Cleven, Y. Cobigo, B. A. Cole, M. P. Comets, P. Constantin, M. Csanad, T. Csorgo, T. Dahms, K. Das, G. David, M. B. Deaton, K. Dehmelt, H. Delagrange, A. Denisov, D. d'Enterria, A. Deshpande, E. J. Desmond, O. Dietzsch, A. Dion, M. Donadelli, J. L. Drachenberg, O. Drapier, A. Drees, A. K. Dubey, A. Durum, V. Dzhordzhadze, Y. V. Efremenko, J. Egdemir, F. Ellinghaus, W. S. Emam, A. Enokizono, H. En'yo, B. Espagnon, S. Esumi, K. O. Eyser, D. E. Fields, M., Jr. Finger, M. Finger, F. Fleuret, S. L. Fokin, B. Forestier, Z. Fraenkel, J. E. Frantz, A. Franz, A. D. Frawley, K. Fujiwara, Y. Fukao, S-Y. Fung, T. Fusayasu, S. Gadrat, I. Garishvili, F. Gastineau, M. Germain, A. Glenn, H. Gong, M. Gonin, J. Gosset, Y. Goto, R. Granier de Cassagnac, N. Grau, S. V. Greene, M. Grosse Perdekamp, T. Gunji, Hans-Åke Gustafsson, T. Hachiya, A. Hadj Henni, C. Haegemann, J. S. Haggerty, M. N. Hagiwara, H. Hamagaki, R. Han, H. Harada, E. P. Hartouni, K. Haruna, M. Harvey, Eva Haslum, K. Hasuko, R. Hayano, M. Heffner, T. K. Hemmick, T. Hester, J. M. Heuser, X. He, H. Hiejima, J. C. Hill, R. Hobbs, M. Hohlmann, M. Holmes, W. Holzmann, K. Homma, B. Hong, T. Horaguchi, D. Hornback, M. G. Hur, T. Ichihara, K. Imai, M. Inaba, Y. Inoue, D. Isenhower, L. Isenhower, M. Ishihara, T. Isobe, M. Issah, A. Isupov, B. V. Jacak, J. Jia, J. Jin, O. Jinnouchi, B. M. Johnson, K. S. Joo, D. Jouan, F. Kajihara, S. Kametani, N. Kamihara, J. Kamin, M. Kaneta, J. H. Kang, H. Kanou, T. Kawagishi, D. Kawall, A. V. Kazantsev, S. Kelly, A. Khanzadeev, J. Kikuchi, D. H. Kim, D. J. Kim, E. Kim, Y-S. Kim, E. Kinney, A. Kiss, E. Kistenev, A. Kiyomichi, J. Klay, C. Klein-Boesing, L. Kochenda, V. Kochetkov, B. Komkov, M. Konno, D. Kotchetkov, A. Kozlov, A. Kral, A. Kravitz, P. J. Kroon, J. Kubart, G. J. Kunde, N. Kurihara, K. Kurita, M. J. Kweon, Y. Kwon, G. S. Kyle, R. Lacey, Y-S. Lai, J. G. Lajoie, A. Lebedev, Y. Le Bornec, S. Leckey, D. M. Lee, M. K. Lee, T. Lee, M. J. Leitch, M. A. L. Leite, B. Lenzi, H. Lim, T. Liska, A. Litvinenko, M. X. Liu, X. Li, X. H. Li, B. Love, D. Lynch, C. F. Maguire, Y. I. Makdisi, A. Malakhov, M. D. Malik, V. I. Manko, Y. Mao, L. Masek, H. Masui, F. Matathias, M. C. McCain, M. McCumber, P. L. McGaughey, Y. Miake, P. Mikes, K. Miki, T. E. Miller, A. Milov, S. Mioduszewski, G. C. Mishra, M. Mishra, J. T. Mitchell, M. Mitrovski, A. Morreale, D. P. Morrison, J. M. Moss, T. V. Moukhanova, D. Mukhopadhyay, J. Murata, S. Nagamiya, Y. Nagata, J. L. Nagle, M. Naglis, I. Nakagawa, Y. Nakamiya, T. Nakamura, K. Nakano, J. Newby, M. Nguyen, B. E. Norman, R. Nouicer, A. S. Nyanin, Joakim Nystrand, E. O'Brien, S. X. Oda, C. A. Ogilvie, H. Ohnishi, I. D. Ojha, H. Okada, K. Okada, M. Oka, O. O. Omiwade, Anders Oskarsson, Ingvar Otterlund, M. Ouchida, K. Ozawa, R. Pak, D. Pal, A. P. T. Palounek, V. Pantuev, V. Papavassiliou, J. Park, W. J. Park, S. F. Pate, H. Pei, J-C. Peng, H. Pereira, V. Peresedov, D. Yu. Peressounko, C. Pinkenburg, R. P. Pisani, M. L. Purschke, A. K. Purwar, H. Qu, J. Rak, A. Rakotozafindrabe, I. Ravinovich, K. F. Read, S. Rembeczki, M. Reuter, K. Reygers, V. Riabov, Y. Riabov, G. Roche, A. Romana, M. Rosati, Sarah Rosendahl, P. Rosnet, P. Rukoyatkin, V. L. Rykov, S. S. Ryu, B. Sahlmueller, N. Saito, T. Sakaguchi, S. Sakai, H. Sakata, V. Samsonov, H. D. Sato, S. Sato, S. Sawada, J. Seele, R. Seidl, V. Semenov, R. Seto, D. Sharma, T. K. Shea, I. Shein, A. Shevel, T-A. Shibata, K. Shigaki, M. Shimomura, T. Shohjoh, K. Shoji, A. Sickles, C. L. Silva, D. Silvermyr, C. Silvestre, K. S. Sim, C. P. Singh, V. Singh, S. Skutnik, M. Slunecka, W. C. Smith, A. Soldatov, R. A. Soltz, W. E. Sondheim, S. P. Sorensen, I. V. Sourikova, F. Staley, P. W. Stankus, Evert Stenlund, M. Stepanov, A. Ster, S. P. Stoll, T. Sugitate, C. Suire, J. P. Sullivan, J. Sziklai, T. Tabaru, S. Takagi, E. M. Takagui, A. Taketani, K. H. Tanaka, Y. Tanaka, K. Tanida, M. J. Tannenbaum, A. Taranenko, P. Tarjan, T. L. Thomas, M. Togawa, A. Toia, J. Tojo, L. Tomasek, H. Torii, R. S. Towell, V-N. Tram, I. Tserruya, Y. Tsuchimoto, S. K. Tuli, Henrik Tydesjö, N. Tyurin, C. Vale, H. Valle, H. W. van Hecke, J. Velkovska, R. Vertesi, A. A. Vinogradov, M. Virius, V. Vrba, E. Vznuzdaev, M. Wagner, D. Walker, X. R. Wang, Y. Watanabe, J. Wessels, S. N. White, N. Willis, D. Winter, C. L. Woody, M. Wysocki, W. Xie, Y. L. Yamaguchi, A. Yanovich, Z. Yasin, J. Ying, S. Yokkaichi, G. R. Young, I. Younus, I. E. Yushmanov, W. A. Zajc, O. Zaudtke, C. Zhang, S. Zhou, J. Zimanyi, L. Zolin

Research output: Contribution to journalArticlepeer-review

Abstract

PHENIX has measured the e(+)e(-) pair continuum in root s(NN) = 200 GeV Au+Au and p+p collisions over a wide range of mass and transverse momenta. The e(+)e(-) yield is compared to the expectations from hadronic sources, based on PHENIX measurements. In the intermediate-mass region, between the masses of the phi and the J/psi meson, the yield is consistent with expectations from correlated c (c) over bar production, although other mechanisms are not ruled out. In the low-mass region, below the phi, the p+p inclusive mass spectrum is well described by known contributions from light meson decays. In contrast, the Au+Au minimum bias inclusive mass spectrum in this region shows an enhancement by a factor of 4.7 +/- 0.4(stat) +/- 1.5(syst) +/- 0.9(model). At low mass (m(ee) < 0.3 GeV/c(2)) and high p(T) (1 < p(T) < 5 GeV/c) an enhanced e(+)e(-) pair yield is observed that is consistent with production of virtual direct photons. This excess is used to infer the yield of real direct photons. In central Au+Au collisions, the excess of the direct photon yield over the p+p is exponential in p(T), with inverse slope T = 221 +/- 19(stat) +/- 19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T-init similar or equal to 300-600 MeV at times of 0.6-0.15 fm/c after the collision are in qualitative agreement with the direct photon data in Au+Au. For low p(T) < 1 GeV/c the low-mass region shows a further significant enhancement that increases with centrality and has an inverse slope of T similar or equal to 100 MeV. Theoretical models underpredict the low-mass, low-p(T) enhancement.
Original languageEnglish
Article number034911
JournalPhysical Review C (Nuclear Physics)
Volume81
Issue number3
DOIs
Publication statusPublished - 2010

Subject classification (UKÄ)

  • Subatomic Physics

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