Energy loss in a fluctuating hydrodynamical background
Abstract
Recently it has become apparent that event-by-event fluctuations in the initial state of hydrodynamical modelling of ultrarelativistic heavy-ion collisions are crucial in order to understand the full centrality dependence of the elliptic flow coefficient v2. In particular, in central collisions the density fluctuations play a major role in generating the spatial eccentricity in the initial state. This raises the question to what degree high PT physics, in particular leading-parton energy loss, which takes place in the background of an evolving medium, is sensitive to the presence of the event-by-event density fluctuations in the background. In this work, we report results for the effects of fluctuations on the nuclear modification factor RAA in both central and noncentral sqrt(sNN) = 200 GeV Au+Au collisions at RHIC. Two different types of energy-loss models, a radiative and an elastic, are considered. In particular, we study the dependence of the results on the assumed spatial size of the density fluctuations, and discuss the angular modulation of RAA with respect to the event plane.