Energy loss of a heavy quark produced in a finite-size quark-gluon plasma

We study the energy loss of an energetic heavy quark produced in a high temperature quark?gluon plasma and travelling a finite distance before emerging in the vacuum. While the retardation time of purely collisional energy loss is found to be of the order of the Debye screening length, we find that the contributions from transition radiation and the Ter?Mikayelian effect do not compensate, leading to an energy loss, the reduction of the zeroth-order (in an opacity expansion) energy loss.