High-pT suppression and elliptic flow from radiative energy loss with realistic bulk medium expansion

Abstract

We investigate nuclear suppression and elliptic flow in A+A reactions using Gyulassy-Levai-Vitev (GLV) radiative energy loss with the covariant transport MPC for bulk medium evolution. At both RHIC and LHC energies, we find that inclusion of realistic transverse expansion for the medium strongly suppresses elliptic flow at high p_T compared to calculations with longitudinal Bjorken expansion only. We argue that this is a generic feature of GLV energy loss. Transverse expansion also enhances the high-p_T suppression, while fluctuations in energy loss with the rescattering location of the jet parton in the medium lead to weaker suppression and smaller elliptic flow. However, unlike the strong reduction of elliptic flow with transverse expansion, these latter effects get nearly washed out once calculations are adjusted to reproduce R_AA in central collisions.