Abstract :
In this proceedings we compare 0th order in opacity medium and vacuum energy loss. We show that, contrary to naive expectations, the difference between medium and vacuum 0th order energy loss is significant, and has to be included in the computation of jet quenching. This is due to the fact that, in addition to the radiative energy loss, medium modified gluon dispersion relation also induces collisional energy loss, which does not exist in the vacuum.
