Neutrinoless double beta decay beyond closure approximation

Abstract

Nuclear matrix elements of neutrinoless double beta decay are calculated without assuming closure approximation, and the calculated elements are compared with those of the closure approximation which has so far been employed and with those of a recently developed approximate procedure (operator expansion method). The nuclear matrix elements are found to be insensitive to model approximations because of the virtual nature of neutrino, indicating that sharp limits on the neutrino mass can be deduced from neutrinoless double beta decay.