Density dependence of nuclear neutrino-pair production

Nuclear decay via neutrino-pair production is found to have a large density dependence because of intermediate electromagnetic couplings to electrons. These are calculated in a relativistic random phase approximation. The decay rate for vector (Fermi) transitions producing electron type neutrino pairs can be enhanced by 105 or more at densities relevant for stellar collapse. Axial-vector (Gamow-Teller) transitions are not enhanced.