  In heavy-ion collisions the created quark-gluon plasma forms a quickly
evolving background, leading to a time dependent radiative behavior of high
momentum partons traversing the medium. We use the Schwinger Keldysh formalism
to describe the jet evolution as a non-equilibrium process including the
Landau-Pomeranschuk-Migdal effect. Concentrating on photon emission, a
comparison of our results to a quasistatic calculation shows good agreement,
leading to the conclusion that the radiative behavior follows the changes in
the medium almost instantaneously.
