  We recently derived, using diagrammatic methods, the leading-order hard
photon emission rate in ultra-relativistic plasmas. This requires a correct
treatment of multiple scattering effects which limit the coherence length of
emitted radiation (the Landau-Pomeranchuk-Migdal effect). In this paper, we
provide a more physical derivation of this result, and extend the treatment to
the case of gluon radiation.
