Abstract
The measurements of azimuthal anisotropy v2 of charged particles with pT of 3-6 GeV/c revealed a saturation pattern of v2 with values that decrease systematically with increasing centrality. This contradicts nondissipative hydrodynamics which predicts a monotonically increasing v2 with increasing pT, but the data may be consistent with dissipative dynamics with finite parton energy loss. The data provide important constraints on the theoretical interpretations of the mechanism of high pT particle production in ultrarelativistic heavy-ion collisions.