Azimuthal dependence of mean pT fluctuation at RHIC
Shengli Huang

Nuclear Science Division, Lawrence Berkeley National Laboratory

Abstract
  The goal of studying the physics of high-energy nuclear collisions
is to understand the properties of matter under extreme conditions. In the
search of phase transition from ordinary nuclear matter to quark-gluon-plasma,
mean pT fluctuation measurement is one of the promising methods.  At RHIC, 
elliptic flow v2 was found to be large compared with results at lower beam 
energies. We believe this is caused by the strong pressure gradient of medium 
developed at  early stage of the collision. In order to understand the 
dynamical origin of mean pT fluctuation and the large value of v2 at RHIC, 
we performed the pT fluctuation analysis in the different azimuthal regions.  
In this talk, we will report STAR preliminary results on the azimuthal 
dependence of pT fluctuations from both 62.4 and 200 GeV Au+Au collisions. 
Centrality dependence of the analysis will also be discussed. We will compare 
our data with model calculations.