Beam energy dependence of dielectron production in Au+Au collisions from STAR at RHIC

19 May 2014, 11:00
20m
helium (darmstadtium)

helium

darmstadtium

Schlossgraben 1 64283 Darmstadt Germany
Contributed Talk Electromagnetic Probes Electromagnetic probes

Speaker

Mr Patrick Huck (LBNL/CCNU)

Description

Bulk-penetrating dielectrons allow for the extraction of direct information from all stages of a heavy ion collision as they serve as electromagnetic probes with negligible final-state interactions. The completion of the Barrel Time-of-Flight detector (TOF) in 2010 has allowed the Solenoid Tracker At RHIC (STAR) to play a unique role in the study of dielectron production with excellent particle identification, low material budget, full azimuthal acceptance at mid-rapidity, and a wide momentum coverage. In combination with the Beam Energy Scan (BES) conducted at RHIC, in particular, STAR presents the unprecedented opportunity to map out a significant portion of the QCD phase diagram within a homogeneous experimental environment. In the quest for a better understanding of strongly interacting nuclear matter the Low-Mass Region (LMR, $M_{ee}$ < 1.1 GeV/$c^2$) of dielectron spectra, on the one hand, provides information about in-medium modifications of the $\rho$-meson's properties. The Intermediate-Mass Region (IMR, 1.1 < $M_{ee}$ < 3 GeV/$c^2$), on the other hand, can provide access to the initial Quark-Gluon Plasma (QGP) temperature as well as a possibly medium-modified correlated charm continuum. In this talk, we will present the energy-dependent study of dielectron production at $\sqrt{s_{NN}}$ of 19.6, 27, 39, and 62.4 GeV. $M_{ee}$ and $p_{\text{T}}$ differential measurements of LMR mass distributions are compared to cocktail simulations of known hadronic sources. The excess yield is further compared to calculations of $\rho$ in-medium modifications. Properties of IMR spectral data will be compared to simulations of semi-leptonic charmed decays.
On behalf of collaboration: STAR

Primary author

Mr Patrick Huck (LBNL/CCNU)

Presentation Materials