Uncertainties in nuclear transition matrix elements forβ+β+andɛβ+modes of neutrinoless positron double-βdecay within the projected Hartree-Fock-Bogoliubov model

Abstract

Uncertainties in the nuclear transition matrix elements ${M}^{(0\ensuremath{\nu})}$ and ${M}^{(0N)}$ of the double-positron emission ${({\ensuremath{\beta}}^{+}{\ensuremath{\beta}}^{+})}_{0\ensuremath{\nu}}$ and electron-positron conversion ${(\ensuremath{\varepsilon}{\ensuremath{\beta}}^{+})}_{0\ensuremath{\nu}}$ modes owing to the exchange of light and heavy Majorana neutrinos, respectively, are calculated for ${}^{96}$Ru, ${}^{102}$Pd, ${}^{106}$Cd, ${}^{124}$Xe, ${}^{130}$Ba, and ${}^{156}$Dy isotopes by employing the PHFB model with four different parametrizations of the pairing plus multipolar two-body interactions and three different parametrizations of the Jastrow short-range correlations. In all cases but for ${}^{130}$Ba the uncertainties are smaller than 14$%$ for light Majorana neutrino exchange and 35$%$ for the exchange of a heavy Majorana neutrino.