Speaker
Description
The study of direct-photon-triggered away-side jets was proposed [1]
as a good probe of parton energy loss because the direct photon
transverse momentum ($p_{T}$) approximates that of recoil parton before
traversing the medium created in heavy-ion collisions. On the other
hand, comparison between the suppression of direct photon- and $\pi^{0}$-
triggered
away-side hadron yields can give information about the path-length and
color-factor dependence of parton energy loss. We report the results of
direct photon-hadron and $\pi^{0}$-hadron azimuthal correlations as a measure of
the away-side jet-like correlated yields in central Au+Au and p+p
collisions at
$\sqrt{s_{NN}}$ 200 GeV in the STAR experiment. The charged-hadron
per-trigger yields at
mid-rapidity ($|\eta| < $1) and for transverse momenta $p_{T}^{assoc} >$ 1.2
GeV/c associated with direct photon and $\pi^{0}$ (for 12 $< p_{T}^{trig} <$ 20 GeV/c)
in central Au+Au
collisions are compared with p+p collisions. The same $z_{T}$
(~$\frac{p_{T}^{assoc}}{p_{T}^{trig}}$) dependence of the suppression is observed for
direct photon and $\pi^{0}$ triggers, within uncertainties. The results are compared with energy-loss-inspired theoretical model predictions.
[1] X.-N. Wang, Z. Huang, and I. Sarcevic, Phys. Rev. Lett. 77, 231
(1996).
