Neutrino scattering and absorption in warm neutron-rich matter*

Neutrino scattering and absorption rates that are important inputs for dynamical simulations of core-collapse supernovae and neutron star mergers are obtained from nuclear matter dynamical structure functions that encode many-body effects from nuclear mean fields and correlations. In this work we employ nuclear interactions from chiral effective field theory to calculate the density and spin response functions of warm beta-equilibrium nuclear matter. We include corrections to the single-particle energies in the mean field approximation as well as vertex corrections resummed in the random phase approximation (RPA). We find that the presence of collective modes in the medium leads to a redistribution of the response function strength to higher energy for neutrino absorption and lower energy for antineutrino absorption. This tends to suppress the absorption rate of electron neutrinos across all relevant energy scales and enhances the electron antineutrino absorption rate at low energy.