Measurements of dielectron production in Au + Au collisions at sNN =200 GeV from the STAR experiment

L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. BordyuzhinJ. Bouchet, A. V. Brandin, I. Bunzarov, T. P. Burton, J. Butterworth, H. Caines, M. Calderón De La Barca Sánchez, J. M. Campbell, D. Cebra, M. C. Cervantes, I. Chakaberia, P. Chaloupka, Z. Chang, S. Chattopadhyay, J. H. Chen, X. Chen, J. Cheng, M. Cherney, W. Christie, G. Contin, H. J. Crawford, S. Das, L. C. De Silva, R. R. Debbe, T. G. Dedovich, J. Deng, A. A. Derevschikov, B. Di Ruzza, L. Didenko, C. Dilks, X. Dong, J. L. Drachenberg, J. E. Draper, C. M. Du, L. E. Dunkelberger, J. C. Dunlop, L. G. Efimov, J. Engelage, G. Eppley, R. Esha, O. Evdokimov, O. Eyser, R. Fatemi, S. Fazio, P. Federic, J. Fedorisin, Z. Feng, P. Filip, Y. Fisyak, C. E. Flores, L. Fulek, C. A. Gagliardi, D. Garand, F. Geurts, A. Gibson, M. Girard, L. Greiner, D. Grosnick, D. S. Gunarathne, Y. Guo, S. Gupta, A. Gupta, W. Guryn, A. Hamad, A. Hamed, R. Haque, J. W. Harris, L. He, S. Heppelmann, S. Heppelmann, A. Hirsch, G. W. Hoffmann, D. J. Hofman, S. Horvat, B. Huang, X. Huang, H. Z. Huang, P. Huck, T. J. Humanic, G. Igo, W. W. Jacobs, H. Jang, K. Jiang, E. G. Judd, K. Jung, S. Kabana, D. Kalinkin, K. Kang, K. Kauder, H. W. Ke, D. Keane, A. Kechechyan, Z. H. Khan, D. P. Kikola, I. Kisel, A. Kisiel, L. Kochenda, D. D. Koetke, T. Kollegger, L. K. Kosarzewski, A. F. Kraishan, P. Kravtsov, K. Krueger, I. Kulakov, L. Kumar, R. A. Kycia, M. A.C. Lamont, J. M. Landgraf, K. D. Landry, J. Lauret, A. Lebedev, R. Lednicky, J. H. Lee, X. Li, C. Li, W. Li, Z. M. Li, Y. Li, X. Li, M. A. Lisa, F. Liu, T. Ljubicic, W. J. Llope, M. Lomnitz, R. S. Longacre, X. Luo, Y. G. Ma, G. L. Ma, L. Ma, R. Ma, N. Magdy, R. Majka, A. Manion, S. Margetis, C. Markert, H. Masui, H. S. Matis, D. McDonald, K. Meehan, N. G. Minaev, S. Mioduszewski, B. Mohanty, M. M. Mondal, D. Morozov, M. K. Mustafa, B. K. Nandi, Md Nasim, T. K. Nayak, G. Nigmatkulov, L. V. Nogach, S. Y. Noh, J. Novak, S. B. Nurushev, G. Odyniec, A. Ogawa, K. Oh, V. Okorokov, D. Olvitt, B. S. Page, R. Pak, Y. X. Pan, Y. Pandit, Y. Panebratsev, B. Pawlik, H. Pei, C. Perkins, A. Peterson, P. Pile, M. Planinic, J. Pluta, N. Poljak, K. Poniatowska, J. Porter, M. Posik, A. M. Poskanzer, N. K. Pruthi, J. Putschke, H. Qiu, A. Quintero, S. Ramachandran, R. Raniwala, S. Raniwala, R. L. Ray, H. G. Ritter, J. B. Roberts, O. V. Rogachevskiy, J. L. Romero, A. Roy, L. Ruan, J. Rusnak, O. Rusnakova, N. R. Sahoo, P. K. Sahu, I. Sakrejda, S. Salur, J. Sandweiss, A. Sarkar, J. Schambach, R. P. Scharenberg, A. M. Schmah, W. B. Schmidke, N. Schmitz, J. Seger, P. Seyboth, N. Shah, E. Shahaliev, P. V. Shanmuganathan, M. Shao, M. K. Sharma, B. Sharma, W. Q. Shen, S. S. Shi, Q. Y. Shou, E. P. Sichtermann, R. Sikora, M. Simko, M. J. Skoby, D. Smirnov, N. Smirnov, L. Song, P. Sorensen, H. M. Spinka, B. Srivastava, T. D.S. Stanislaus, M. Stepanov, R. Stock, M. Strikhanov, B. Stringfellow, M. Sumbera, B. Summa, X. Sun, Z. Sun, X. M. Sun, Y. Sun, B. Surrow, N. Svirida, M. A. Szelezniak, A. H. Tang, Z. Tang, T. Tarnowsky, A. N. Tawfik, J. H. Thomas, A. R. Timmins, D. Tlusty, M. Tokarev, S. Trentalange, R. E. Tribble, P. Tribedy, S. K. Tripathy, B. A. Trzeciak, O. D. Tsai, T. Ullrich, D. G. Underwood, I. Upsal, G. Van Buren, G. Van Nieuwenhuizen, M. Vandenbroucke, R. Varma, A. N. Vasiliev, R. Vertesi, F. Videbæk, Y. P. Viyogi, S. Vokal, S. A. Voloshin, A. Vossen, G. Wang, Y. Wang, F. Wang, Y. Wang, H. Wang, J. S. Wang, J. C. Webb, G. Webb, L. Wen, G. D. Westfall, H. Wieman, S. W. Wissink, R. Witt, Y. F. Wu, Z. G. Xiao, W. Xie, K. Xin, Q. H. Xu, Z. Xu, H. Xu, N. Xu, Y. F. Xu, Q. Yang, Y. Yang, S. Yang, Y. Yang, C. Yang, Z. Ye, P. Yepes, L. Yi, K. Yip, I. K. Yoo, N. Yu, H. Zbroszczyk, W. Zha, X. P. Zhang, J. Zhang, Y. Zhang, J. Zhang, J. B. Zhang, S. Zhang, Z. Zhang, J. Zhao, C. Zhong, L. Zhou, X. Zhu, Y. Zoulkarneeva, M. Zyzak

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Abstract

We report on measurements of dielectron (e+e-) production in Au+Au collisions at a center-of-mass energy of 200 GeV per nucleon-nucleon pair using the STAR detector at BNL Relativistic Heavy Ion Collider. Systematic measurements of the dielectron yield as a function of transverse momentum (pT) and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region (Mee<1GeV/c2). This enhancement cannot be reproduced by the ρ-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of 0.30-0.76GeV/c2, integrated over the full pT acceptance, the enhancement factor is 1.76±0.06(stat.)±0.26(sys.)±0.29(cocktail). The enhancement factor exhibits weak centrality and pT dependence in STAR's accessible kinematic regions, while the excess yield in this invariant-mass region as a function of the number of participating nucleons follows a power-law shape with a power of 1.44±0.10. Models that assume an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess in these measurements. Additionally, we report on measurements of ω- and φ-meson production through their e+e- decay channel. These measurements show good agreement with Tsallis blast-wave model predictions, as well as, in the case of the φ meson, results through its K+K- decay channel. In the intermediate invariant-mass region (1.1<Mee<3GeV/c2), we investigate the spectral shapes from different collision centralities. Physics implications for possible in-medium modification of charmed hadron production and other physics sources are discussed.

Original languageEnglish
Article number024912
JournalPhysical Review C - Nuclear Physics
Volume92
Issue number2
DOIs
StatePublished - Aug 24 2015
Externally publishedYes

Funding

FundersFunder number
National Science Foundation1067907

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