Transverse diffusion (“”) at weak coupling

We show that the transport coefficient , describing momentum diffusion for fast jets moving in the quark-gluon plasma, receives large O(g) corrections from plasma effects which we explicitly calculate, at weak coupling. Our approach is based on an “Euclideanization” property of classical physics near the light-cone, which simplifies drastically this calculation and might open up a new possibility for the lattice study of these effects.