Diagonal and Off-Diagonal Density Fluctuations in Hot Nuclear Matter, and Applications to Neutrino Transport in Supernovae

We calculate the effects of interactions on the density fluctuations of an n, p, e plasma. The scattering of neutrinos arising from the Fermi part of the neutral current interactions with protons, under supernova conditions, is practically extinguished by Coulomb effects in the plasma. Charged-current reactions are discussed in terms of off-diagonal density fluctuations. Inclusion of the symmetry energy term in the nuclear interaction gives rise to a large reduction in the Fermi part of the cross section for ν+n→e^-+p.