The QCD collisional energy loss revised

Abstract

It is shown that to leading order the QCD collisional energy loss reads $dE/dx \sim \alpha(m_D^2)T^2$. Compared to prevalent expressions, $dE^B/dx \sim \alpha^2 T^2 \ln(ET/m_D^2)$, which could be considered adaptions of the (QED) Bethe-Bloch formula, the rectified result takes into account the running coupling, as dictated by renormalization. As one significant consequence, due to asymptotic freedom, the collisional energy loss becomes independent of the jet energy $E$. Some implications with regard to heavy ion collisions are pointed out.