Shell Model description of the beta beta decay of 136Xe

TL;DR

This paper employs a shell model approach to analyze the two-neutrino double beta decay of 136Xe, comparing theoretical calculations with recent experimental data to refine nuclear matrix element estimates.

Contribution

The study applies a consistent shell model framework and effective interaction to both two-neutrino and neutrinoless double beta decay calculations of 136Xe, incorporating recent experimental data for improved accuracy.

Findings

Calculated nuclear matrix element M(2nu)=0.025 MeV^(-1)

Experimental value of M(2nu)=0.019(2) MeV^(-1)

Good agreement within uncertainties

Abstract

We study in this letter the double beta decay of 136Xe with emission of two neutrinos which has been recently measured by the EXO-200 collaboration. We use the same shell model framework, valence space, and effective interaction that we have already employed in our calculation of the nuclear matrix element (NME) of its neutrinoless double beta decay. Using the quenching factor of the Gamow-Teller operator which is needed to reproduce the very recent high resolution 136Xe (3He, t)136Cs data, we obtain a nuclear matrix element M(2nu)=0.025 MeV^(-1) compared with the experimental value M(2nu)=0.019(2) MeV^(-1).