Neutrinoless double positron decay and positron emitting electron capture in the interacting boson model

TL;DR

This paper calculates nuclear matrix elements for neutrinoless double positron decay and positron emitting electron capture using the IBM-2 model, aiding the search for neutrino mass and lepton number violation.

Contribution

It provides new nuclear matrix element calculations for rare decay modes within the interacting boson model, expanding understanding of positron-related lepton number violating processes.

Findings

Calculated nuclear matrix elements for multiple isotopes.

Estimated half-lives for neutrinoless double positron decay.

Enhanced theoretical framework for experimental searches.

Abstract

Neutrinoless double-$\beta$ decay is of fundamental importance for determining the neutrino mass. Although double electron ($\beta^-\beta^-$) decay is the most promising mode, in very recent years interest in double positron ($\beta^+\beta^+$) decay, positron emitting electron capture ($EC\beta^+$), and double electron capture ($ECEC$) has been renewed. We present here results of a calculation of nuclear matrix elements for neutrinoless double-$\beta^+$ decay and positron emitting electron capture within the framework of the microscopic interacting boson model (IBM-2) for $^{58}$Ni, $^{64}$Zn, $^{78}$Kr, $^{96}$Ru, $^{106}$Cd, $^{124}$Xe, $^{130}$Ba, and $^{136}$Ce decay. By combining these with a calculation of phase space factors we calculate expected half-lives.