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)
