Naslov
Measurements of Dielectron Production in Au+Au Collisions at √sNN = 200 GeV from the STAR Experiment

Autori
Adamczyk, L. ... ; Planinić, Mirko ; ... ; Poljak, Nikola ; ... ; Zyzak, M.

Izvornik
Physical review. C. Nuclear physics (0556-2813) 92 (2015), 2; 24912, 35

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
dielectron ; STAR

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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