Charged-current neutrino interactions in core-collapse supernovae in a virial expansion

Core-collapse supernovae may depend sensitively on charged-current neutrino interactions in warm, low-density, neutron-rich matter. A proton in neutron-rich matter is more tightly bound than is a neutron. This energy shift Delta U increases the electron energy in nu(e) + n -> p + e, increasing the available phase space and absorption cross section. Likewise Delta U decreases the positron energy in (nu) over bar (e) + p -> n + e(+), decreasing the phase space and cross section. We have calculated Delta U using a model-independent virial expansion and we find that Delta U is much larger, at low densities, than the predictions of many mean-field models. Therefore Delta U could have a significant impact on charged-current neutrino interactions in supernovae. Preliminary simulations of the accretion phase of core-collapse supernovae find that Delta U increases (nu) over bar (e) energies and decreases the nu(e) luminosity. DOI: 10.1103/PhysRevC.86.065806