Dielectron production in Au + Au collisions at √sNN = 200 GeV

Adare, A. and Makek, Mihael and Zou, L. (PHENIX Collaboration) (2016) Dielectron production in Au + Au collisions at √sNN = 200 GeV. Physical Review C, 93 (1). pp. 14904-34. ISSN 0556-2813

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We present measurements of e+e− production at midrapidity in Au + Au collisions at √sNN = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass (mee < 5 GeV/c2) and pair transverse momentum (pT < 5 GeV/c) for minimum bias and for five centrality classes. The e+e− yield is compared to the expectations from known sources. In the low-mass region (mee = 0.30–0.76 GeV/c2) there is an enhancement that increases with centrality and is distributed over the entire pair pT range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to 2.3 ± 0.4(stat) ± 0.4(syst) ± 0.2(model) or to 1.7 ± 0.3(stat) ± 0.3(syst) ± 0.2(model) for minimum bias collisions when the open heavy-flavor contribution is calculated with PYTHIA or MC@NLO, respectively. The inclusive mass and pT distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the ρ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region (mee = 1.2–2.8 GeV/c2), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

Item Type: Article
Date: 11 January 2016
Subjects: NATURAL SCIENCES > Physics
Additional Information: Copyright (2016) by the American Physical Society. Received 5 October 2015; published 11 January 2016.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 03 Feb 2016 13:48
Last Modified: 29 Nov 2017 17:16
URI: http://digre.pmf.unizg.hr/id/eprint/4499

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