Nuclear structure calculations for two-neutrino double-beta decay

TL;DR

This paper presents a detailed microscopic theoretical study of two-neutrino double-beta decay in several isotopes, comparing calculated nuclear matrix elements and Gamow-Teller strength distributions with experimental data to improve understanding of decay mechanisms.

Contribution

It introduces a comprehensive microscopic approach using deformed mean fields and QRPA to analyze double-beta decay and compares results with experimental charge-exchange and beta decay data.

Findings

Good agreement between calculated and experimental Gamow-Teller strengths.

Nuclear matrix elements align with measured half-lives.

Analysis supports single-state and low-lying-state dominance hypotheses.

Abstract

We study the two-neutrino double-beta decay in 76Ge, 116Cd, 128Te, 130Te, and 150Nd, as well as the two Gamow-Teller branches that connect the double-beta decay partners with the states in the intermediate nuclei. We use a theoretical microscopic approach based on a deformed selfconsistent mean field with Skyrme interactions including pairing and spin-isospin residual forces, which are treated in a proton-neutron quasiparticle random-phase approximation. We compare our results for Gamow-Teller strength distributions with experimental information obtained from charge-exchange reactions. We also compare our results for the two-neutrino double-beta decay nuclear matrix elements with those extracted from the measured half-lives. Both single-state and low-lying-state dominance hypotheses are analyzed theoretically and experimentally making use of recent data from charge-exchange reactions and beta decay of the intermediate nuclei.