Neutrinoless double electron capture

TL;DR

This paper calculates nuclear matrix elements and prefactors for neutrinoless double electron capture in several isotopes, providing estimates of half-lives relevant for neutrino mass research.

Contribution

It presents new calculations of nuclear matrix elements and prefactors for neutrinoless double electron capture using the IBM-2 model, aiding experimental searches.

Findings

Half-life estimates are comparable to neutrinoless double positron decay.

Predicted half-lives are significantly longer than neutrinoless double beta minus decay.

Results help guide experimental detection efforts.

Abstract

Direct determination of the neutrino mass is at the present time one of the most important aims of experimental and theoretical research in nuclear and particle physics. A possible way of detection is through neutrinoless double electron capture, $0\nu ECEC$. This process can only occur when the energy of the initial state matches precisely that of the final state. We present here a calculation of prefactors (PF) and nuclear matrix elements (NME) within the framework of the microscopic interacting boson model (IBM-2) for $^{124}$Xe, $^{152}$Gd, $^{156}$Dy, $^{164}$Er, and $^{180}$W. From PF and NME we calculate the expected half-lives and obtain results that are of the same order as those of $ 0\nu \beta^+\beta^+$ decay, but considerably longer than those of $0\nu \beta^-\beta^-$ decay.