Rethinking the QCD collisional energy loss

Abstract

It is shown that to leading order the collisional energy loss of an energetic parton in the hot quark gluon plasma reads dE/dx∼α(m_D ²)T², where the scale of the coupling is determined by the (parametrically soft) Debye screening mass. Compared to previous expressions derived by Bjorken and other authors, dE^B/dx∼α²T²ln(ET/m_D ²), the rectified result takes into account the running of the coupling, as dictated by quantum corrections beyond tree level. As one significant consequence, due to asymptotic freedom, the QCD collisional energy loss becomes independent of the jet energy in the limit E≫T. It is argued why this resummation-improved perturbative result is useful to (re-) estimate the collisional energy loss for temperatures relevant in heavy ion phenomenology.