PHENIX Measurements of Azimuthal Anisotropy for $\ddot{I}{€}^0$ Production at High $p_T$ in Au+Au Collisions at $\sqrt{s_{NN}}=200$GeV

Abstract

An improved measurement of $v_2$ for $\ddot{I}{€}^0$ in a broad range of $p_T$ and centrality is presented. By combining $v_2$ with the $R_{AA}$, we provide new insights on jet-medium interactions. We show that current pQCD energy loss models cannot describe the suppression of the $\ddot{I}{€}^0$ as a function of the angle with respect to the reaction plane. Our result could help to resolve the factor of 4 differences in the predicted transport coefficients among these models. Alternatively, it may suggest that non-perturbative effects associated with the strongly coupled QGP are important, and new theoretical developments are needed to fully understand the jet medium interactions.

4 pages, 4 figures, 21st International Conference On Ultra-Relativistic Nucleus-Nucleus Collisions (QM2009) 30 Mar - 4 Apr 2009, Knoxville, Tennessee