  We investigate the medium modification of a partonic jet shower traversing in
a hot quark-gluon plasma. We derive and solve a differential equation that
governs the evolution of the radiated gluon spectrum as the jet propagates
through the medium. Energy contained inside the jet cone is lost by dissipation
through elastic collisions with the medium and by scattering of shower partons
to larger angles. We find that the jet energy loss at early times is dominated
by medium effects on the vacuum radiation, and by medium-induced radiation
effects at late times. We compare our numerical results for the nuclear
modification of the di-jet asymmetry with that recently reported by the ATLAS
collaboration.
