Nuclear matrix elements for Majoron-emitting double- β decay

Abstract

A complete calculation of the nuclear matrix elements (NMEs) for Majoron emitting neutrinoless double beta decay within the framework of IBM-2 for spectral indices $n=1,3,7$ is presented. By combining the results of this calculation with previously calculated phase-space factors (PSFs) we give predictions for expected half-lives. By comparing with experimental limits on the half-lives we set limits on the coupling constants $\ensuremath{\langle}{g}_{ee}^{M}\ensuremath{\rangle}$ of all proposed Majoron-emitting models.