Speaker
Kolja Kauder
(University of Illinois at Chicago)
Description
Hard scatterings of partons provide a valuable colored probe of the
strongly-coupled medium created in ultra-relativistic heavy ion
collisions. These hard scatterings can be studied by means of angular
correlations of charged hadrons with respect to a high transverse
momentum trigger particle. Several recent two-particle correlation
studies indicate that A+A collision dynamics evolve significantly
with collision centrality. They specifically reveal the presence of
unexpected strong away-side deformation and the development of a
long-range "ridge" in correlation measured as a function of
$\Delta\eta$ vs $\Delta\phi$. The detailed physics mechanisms
responsible for these features however remain under active
investigation.
We will present preliminary results of a new di-hadron correlation
analysis, measured as a function of $\Delta \phi$ vs $\Delta \eta$,
for identified high-pT triggers from the high-statistics 200 GeV Au+Au
data sample collected by the STAR experiment at RHIC during Run-10.
The relativistic rise of the ionization energy loss dependence of
particles measured in the STAR TPC is used to obtain a statistical
separation of charged pions, kaons, and protons. The $\Delta \phi$ vs
$\Delta \eta$ correlations measured in this work extend earlier
measurements of azimuthal correlations (in $\Delta \phi$ only) with
identified hadron triggers, which, admittedly with large
uncertainties, reported no significant dependence on a leading hadron
identity. The added $\Delta \eta$ dimension and improved statistics
reveal a rich set of new features: the near-side ($ |\Delta \phi|<1$)
associated hadron distributions with respect to high-pT pion, kaon
and proton triggers exhibit distinctly different features
for both "ridge" (large $\Delta \eta$ and small $\Delta \phi$) and
"jet-like" ($ |\Delta \phi|<0.7$ excluding the ridge) particles.
We will discuss the implications of these results in the context of
the existing models and possible connection of the leading hadron ID
with the color-charge and/or flavor of a hard-scattered parton.
Author
Kolja Kauder
(University of Illinois at Chicago)
