Collisional energy loss in a finite size QCD matter

Computation of collisional energy loss in a finite size QCD medium has become crucial to obtain reliable predictions for jet quenching in ultrarelativistic heavy ion collisions. We here compute this energy loss up to the zeroth order in opacity. Our approach consistently treats both soft and hard contributions to the collisional energy loss. Consequently, it removes the unphysical energy gain in a region of lower momenta obtained by previous computations. Most importantly, we show that for characteristic QCD medium scales, finite size effects on the collisional energy loss are not significant.