Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au + Au collisions at √sNN = 19.6 and 200 GeV

Adamczyk, L. and Planinić, Mirko and Poljak, Nikola and Zyzak, M. (STAR Collaboration) (2015) Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au + Au collisions at √sNN = 19.6 and 200 GeV. Physics Letters B, 750. pp. 64-71. ISSN 0370-2693

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Abstract

The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity |yee | < 1 in minimum-bias Au + Aucollisions at √sNN = 19.6 and 200 GeV. The excess mass spectra are consistently described by a model calculation with a broadened ρ spectral function for Mee < 1.1 GeV/c2. The integrated dielectron excess yield at √sNN = 19.6 GeVfor 0.4 < Mee < 0.75 GeV/c2, normalized to the charged particle multiplicity at mid-rapidity, has a value similar to that in In + √ In collisions at √sNN = 17.3 GeV. For √sNN = 200 GeV, the normalized excess yield in central collisions is higher than that at √sNN = 17.3 GeVand increases from peripheral to central collisions. These measurements indicate that the lifetime of the hot, dense medium created in central Au + Aucollisions at √sNN = 200 GeVis longer than those in peripheral collisions and at lower energies.

Item Type: Article
Date: 12 November 2015
Subjects: NATURAL SCIENCES > Physics
Additional Information: © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3. Received 23 January 2015, Revised 25 June 2015, Accepted 18 August 2015, Available online 20 August 2015
Divisions: Faculty of Science > Department of Physics
Publisher: Elsevier
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 11 Feb 2016 16:47
Last Modified: 17 Feb 2016 11:21
URI: http://digre.pmf.unizg.hr/id/eprint/4512

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