Detailed measurement of the e+e- pair continuum in p+p and Au+Au collisions at √sNN=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. Csanád, T. Csörgo, 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. 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, H. Å 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, E. 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. Král, 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. Liška, 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. Mašek, H. Masui, F. Matathias, M. C. McCain, M. McCumber, P. L. McGaughey, Y. Miake, P. Mikeš, 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, J. Nystrand, E. O'Brien, S. X. Oda, C. A. Ogilvie, H. Ohnishi, I. D. Ojha, H. Okada, K. Okada, M. Oka, O. O. Omiwade, A. Oskarsson, I. 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, S. S.E. 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. Slunečka, W. C. Smith, A. Soldatov, R. A. Soltz, W. E. Sondheim, S. P. Sorensen, I. V. Sourikova, F. Staley, P. W. Stankus, E. 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. Tarján, T. L. Thomas, M. Togawa, A. Toia, J. Tojo, L. Tomášek, H. Torii, R. S. Towell, V. N. Tram, I. Tserruya, Y. Tsuchimoto, S. K. Tuli, H. 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. Zimányi, L. Zolin

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Abstract

PHENIX has measured the e+e- pair continuum in √sNN=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 φ and the J/ψ meson, the yield is consistent with expectations from correlated cc□ production, although other mechanisms are not ruled out. In the low-mass region, below the φ, 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. 4stat±1.5syst±0.9model. At low mass (mee<0.3□ GeV/c2) and high pT (1<pT<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 pT, with inverse slope T=221±19stat±19syst□ MeV. Hydrodynamical models with initial temperatures ranging from Tinit□□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 pT<1□ GeV/c the low-mass region shows a further significant enhancement that increases with centrality and has an inverse slope of T□□100□ MeV. Theoretical models underpredict the low-mass, low-pT enhancement.

Original languageEnglish
Article number034911
JournalPhysical Review C - Nuclear Physics
Volume81
Issue number3
DOIs
Publication statusPublished - 2010 Mar 29

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

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    Adare, A., Afanasiev, S., Aidala, C., Ajitanand, N. N., Akiba, Y., Al-Bataineh, H., Alexander, J., Al-Jamel, A., Aoki, K., Aphecetche, L., Armendariz, R., Aronson, S. H., Asai, J., Atomssa, E. T., Averbeck, R., Awes, T. C., Azmoun, B., Babintsev, V., Baksay, G., ... Zolin, L. (2010). Detailed measurement of the e+e- pair continuum in p+p and Au+Au collisions at √sNN=200 GeV and implications for direct photon production. Physical Review C - Nuclear Physics, 81(3), [034911]. https://doi.org/10.1103/PhysRevC.81.034911