Neutrinoless double- decay in SU(2)×U(1) theories

Abstract

It is shown that gauge theories give contributions to neutrinoless double decay [()0] which are not covered by the standard parametrizations. While probably small, their existence raises the question of whether the observation of ()0 implies the existence of a Majorana mass term for the neutrino. For a "natural" gauge theory we argue that this is indeed the case. © 1982 The American Physical Society.