MULTIPLE-SCATTERING SUPPRESSION OF THE BREMSSTRAHLUNG EMISSION OF NEUTRINOS AND AXIONS IN SUPERNOVAE

In a supernova core the nucleon collision rate GAMMA-coll far exceeds the oscillation frequency of neutrino or axion radiation originating from nucleon bremsstrahlung processes of the type NN --> NN + vvBAR or a. Therefore, including the imaginary part of the self-energy in the effective nucleon propagator, the rate for such processes is suppressed by a factor [1 + (GAMMA-coll/xi-T)2]-1, where xi is a numerical factor and T is the temperature. Previous SN 1987A bounds on axions, right-handed neutrinos, and other particles must be relaxed accordingly.