Renormalization of the jet-quenching parameter

We study the radiative processes that affect the propagation of a high energy gluon in a dense medium, such as a quark-gluon plasma. In particular, we investigate the role of the large double logarithmic corrections, similar to alpha(s) ln(2) L/tau(0), that were recently identified in the study of p(perpendicular to)-broadening by Liou, Mueller and Wu. We show that these large corrections can be reabsorbed in a renormalization of the jet quenching parameter controlling both momentum broadening and energy loss. We argue that the probabilistic description of these phenomena remains valid, in spite of the large non-locality in time of the radiative corrections. The renormalized jet-quenching parameter is enhanced compared to its standard perturbative estimate. As a particular consequence, the radiative energy loss scales with medium size L as L2+gamma, with gamma = 2 root alpha N-s(c)/pi, as compared to the standard scaling in L-2. (C) 2014 Elsevier B.V. All rights reserved.