Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au plus Au collisions at root(NN)-N-S=19.6 and 200 GeV

0454034 - ÚJF 2016 RIV NL eng J - Journal Article
Adamczyk, L. - Bielčík, J. - Bielčíková, Jana - Chaloupka, P. - Federič, Pavol - Rusňák, Jan - Rusňáková, O. - Šumbera, Michal - Tlustý, David - Trzeciak, B. A. - Vértési, Robert … Total 336 authors
Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au plus Au collisions at root(NN)-N-S=19.6 and 200 GeV.
Physics Letters. B. Roč. 750, NOV (2015), s. 64-71. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA ČR GA13-20841S
Institutional support: RVO:61389005
Keywords : STAR collaboration * nucleus-nucleus collisions * CERN-SPS
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders
Impact factor: 4.787, year: 2015

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 vertical bar Y-ee vertical bar <1 in minimum-bias Au + Au collisions at root(NN)-N-S and 200 GeV. The excess mass spectra are consistently described by a model calculation with a broadened p spectral function for Mee <1.1 GeV/c2. The integrated dielectron excess yield at root(NN)-N-S= 19.6 GeV for 0.4 < M-ee <0.75 GeV/c(2), normalized to the charged particle multiplicity at mid-rapidity, has a value similar to that in In + In collisions at root(NN)-N-S = 17.3 GeV. For root(NN)-N-S = 200 GeV, the normalized excess yield in central collisions is higher than that at root(NN)-N-S = 17.3 GeV and increases from peripheral to central collisions. These measurements indicate that the lifetime of the hot, dense medium created in central Au + Au collisions at root(NN)-N-S = 200 GeV is longer than those in peripheral collisions and at lower energies.
Permanent Link: http://hdl.handle.net/11104/0254730