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

Scientific paper - Original scientific paper

• Author: L. Adamczyk
• Author: ...
• Author: Mirko Planinić
• Author: ...
• Author: Nikola Poljak
• Author: ...
• Author: M. Zyzak
• Collaboration: STAR Collaboration
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

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 (p_T) and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region (M_ee<1GeV/c^2). 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/c^2, 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<M_ee<3GeV/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.

• Keywords (english): dielectron; STAR
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical Review C - Nuclear Physics
• Numbering: vol. 92, no. 2, 024912
• p-ISSN: 0556-2813
• e-ISSN: 1089-490X
• DOI: https://doi.org/10.1103/PhysRevC.92.024912
• URN:NBN: urn:nbn:hr:217:347048
• Publication: 2015
• Document URL: http://link.aps.org/doi/10.1103/PhysRevC.92.024912
• Type of resource: Text
• Access conditions: Open access
• Public note: Copyright (2015) by the American Physical Society. Received 9 April 2015; Published 24 August 2015.
• Created on: 2020-01-18 18:15:10