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

  • Author(s): Adamczyk, L
  • Adkins, JK
  • Agakishiev, G
  • Aggarwal, MM
  • Ahammed, Z
  • Alekseev, I
  • Alford, J
  • Aparin, A
  • Arkhipkin, D
  • Aschenauer, EC
  • Averichev, GS
  • Banerjee, A
  • Bellwied, R
  • Bhasin, A
  • Bhati, AK
  • Bhattarai, P
  • Bielcik, J
  • Bielcikova, J
  • Bland, LC
  • Bordyuzhin, IG
  • Bouchet, J
  • Brandin, AV
  • Bunzarov, I
  • Burton, TP
  • Butterworth, J
  • Caines, H
  • Calderón De La Barca Sánchez, M
  • Campbell, JM
  • Cebra, D
  • Cervantes, MC
  • Chakaberia, I
  • Chaloupka, P
  • Chang, Z
  • Chattopadhyay, S
  • Chen, JH
  • Chen, X
  • Cheng, J
  • Cherney, M
  • Christie, W
  • Contin, G
  • Crawford, HJ
  • Das, S
  • De Silva, LC
  • Debbe, RR
  • Dedovich, TG
  • Deng, J
  • Derevschikov, AA
  • Di Ruzza, B
  • Didenko, L
  • Dilks, C
  • Dong, X
  • Drachenberg, JL
  • Draper, JE
  • Du, CM
  • Dunkelberger, LE
  • Dunlop, JC
  • Efimov, LG
  • Engelage, J
  • Eppley, G
  • Esha, R
  • Evdokimov, O
  • Eyser, O
  • Fatemi, R
  • Fazio, S
  • Federic, P
  • Fedorisin, J
  • Feng, Z
  • Filip, P
  • Fisyak, Y
  • Flores, CE
  • Fulek, L
  • Gagliardi, CA
  • Garand, D
  • Geurts, F
  • Gibson, A
  • Girard, M
  • Greiner, L
  • Grosnick, D
  • Gunarathne, DS
  • Guo, Y
  • Gupta, S
  • Gupta, A
  • Guryn, W
  • Hamad, A
  • Hamed, A
  • Haque, R
  • Harris, JW
  • He, L
  • Heppelmann, S
  • Heppelmann, S
  • Hirsch, A
  • Hoffmann, GW
  • Hofman, DJ
  • Horvat, S
  • Huang, B
  • Huang, X
  • Huang, HZ
  • Huck, P
  • Humanic, TJ
  • Igo, G
  • et al.
Abstract

© 2015 American Physical Society. ©2015 American Physical Society. 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

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