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          Institute: MPI für Physik     Collection: YB 2016     Display Documents

ID: 716321.0, MPI für Physik / YB 2016
Measurements of Dielectron Production in Au+Au Collisions at sqrt{s_NN}=200 GeV from the STAR Experiment
Authors:STAR Collaboration; Adamczyk, L.; Schmitz, N.; Seyboth, P.; et al.
Date of Publication (YYYY-MM-DD):2015
Title of Journal:Physical Review C
Journal Abbrev.:Phys.Rev.C
Issue / Number:92
Start Page:024912
Audience:Not Specified
Intended Educational Use:No
Abstract / Description: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 RHIC. Systematic measurements of the dielectron yield as a function of transverse momentum p_T and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region M_{ee}< 1 GeV/c^2. This enhancement cannot be reproduced by the rho-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of 0.30- 0.76 GeV/c^2, integrated over the full p_T acceptance, the enhancement factor is 1.76 pm 0.06 (stat.) pm 0.26 (sys.) pm 0.29 (cocktail). The enhancement factor exhibits weak centrality and p_T 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 pm 0.10. Models that assume an in-medium broadening of the rho meson spectral function consistently describe the observed excess in these measurements. Additionally, we report on measurements of omega and phi$-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 phi-meson, results through its K^+K^- decay channel. In the intermediate invariant-mass region (1.1<M_{ee}< 3 GeV/c^2), 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.
Classification / Thesaurus:STAR
Comment of the Author/Creator:27 pages; 27 figures
External Publication Status:published
Document Type:Article
Communicated by:MPI für Physik
Affiliations:MPI für Physik
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