Nuclear matrix element for two neutrino double beta decay from 136Xe

TL;DR

This paper evaluates the nuclear matrix element for two-neutrino double beta decay of 136Xe using the FSQP model, incorporating experimental data, and finds results consistent with observations, enhancing understanding of nuclear decay processes.

Contribution

The study applies the FSQP model with experimental GT strengths to accurately evaluate the 2 neutrino DBD matrix element for 136Xe, a semi-magic nucleus.

Findings

The evaluated matrix element aligns with observed values.

The 2 neutrino DBD is highly suppressed in 136Xe.

The method integrates charge exchange and beta decay data.

Abstract

The nuclear matrix element for the two neutrino double beta decay (DBD) of 136Xe was evaluated by FSQP (Fermi Surface Quasi Particle model), where experimental GT strengths measured by the charge exchange reaction and those by the beta decay rates were used. The 2 neutrino DBD matrix element is given by the sum of products of the single beta matrix elements via low-lying (Fermi Surface) quasi-particle states in the intermediate nucleus. 136Xe is the semi-magic nucleus with the closed neutron-shell, and the beta + transitions are almost blocked. Thus the 2 neutrino DBD is much suppressed. The evaluated 2 neutrino DBD matrix element is consistent with the observed value.