Phase space factors for $\beta^+\beta^+$ decay and competing modes of double-$\beta$ decay

TL;DR

This paper provides a comprehensive and improved calculation of phase space factors for various double-beta decay modes, incorporating detailed electron wave functions and screening effects, aiding in the interpretation of experimental results.

Contribution

It introduces a complete calculation of phase space factors for multiple double-beta decay modes using exact Dirac wave functions with finite nuclear size and screening effects.

Findings

Calculated phase space factors for multiple decay modes.

Included detailed positron spectra and angular correlations.

Enhanced accuracy over previous models.

Abstract

A complete and improved calculation of phase space factors (PSF) for $2\nu\beta^+\beta^+$ and $0\nu\beta^+\beta^+$ decay, as well as for the competing modes $2\nu EC\beta^+$, $0\nu EC\beta^+$, and $2\nu ECEC$, is presented. The calculation makes use of exact Dirac wave functions with finite nuclear size and electron screening and includes life-times, single and summed positron spectra, and angular positron correlations.