Beam Energy Dependence of Dielectron Production in Au+Au Collisions from STAR at RHIC

Abstract

We present the energy-dependent study of dielectron production in 0-80% minimum-bias Au+Au collisions at $\sqrt{s_{NN}}$ energies of 19.6, 27, 39, and 62.4 GeV in STAR. Invariant mass ($M_{ee}$) and transverse momentum ($p_T$) differential measurements of dielectron yields are compared to cocktail simulations of known hadronic sources and semi-leptonic charmed decays. The enhancement (excess yield) prominent in the Low-Mass Region (LMR) over the cocktail at all energies, is further compared to calculations of $\rho$ in-medium modifications. Within statistical and systematic uncertainties, we find that the model consistently describes this enhancement from SPS up to top RHIC energies in its $M_{ee}$- as well as $p_T$-dependence. Dielectron measurements drive the statistics for the future BES Phase-II program, which promises to improve our understanding of the LMR enhancement's trend with total baryon densities.

4 pages, 3 figures, to be published in Nuclear Physics A, Proceedings of Quark Matter Conference 2014, see http://qm2014.gsi.de/

References in corpus (6)

• NA60 results on thermal dimuons
• Modification of the rho meson detected by low-mass electron-positron pairs in central Pb-Au collisions at 158 A GeV/c
• Dielectron Mass Spectra from Au+Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV
• Systematics of Kinetic Freeze-out Properties in High Energy Collisions from STAR
• Di-electron spectrum at mid-rapidity in $p+p$ collisions at $\sqrt{s}=200$ GeV
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