On the suppression of the gluon radiation for quark jets penetrating a dense quark gas

Suppression of the gluon-emission probability due to secondary scattering (the Landau-Pomeranchuk effect) is considered for an ultra-relativistic quark penetrating a dense gas of thermal quarks. With some appeal to QED, a simple expression for the suppression factor is obtained which reveals strong damping throughout the gluon spectrum for gas densities typical of nuclear matter. The suppression, which is due to multiple rather than single scattering, is in particular pronounced for soft gluon emission. The obtained reduction factor is believed to describe the damping of the Abelian radiation component to within a factor of (sqrt 2 ) . For the non-Abelian component comparison of emission and scattering angles hints at a suppression comparable to that pertaining to the Abelian component.