Overlap of quasiparticle random-phase approximation states for nuclear matrix elements of the neutrino-less double beta decay

TL;DR

This paper develops a method to accurately calculate the overlap of QRPA excited states in different nuclei, which is crucial for evaluating nuclear matrix elements in neutrino-less double beta decay.

Contribution

It introduces a rigorous formulation for QRPA state overlaps using explicit ground state equations, improving the precision of nuclear matrix element calculations.

Findings

Overlap calculation method demonstrated on two nuclei

Effectiveness of truncation schemes validated

Potential impact on neutrino-less double beta decay studies

Abstract

Quasiparticle random-phase approximation (QRPA) is applied to two nuclei, and overlap of the QRPA excited states based on the different nuclei is calculated. The aim is to calculate the overlap of intermediate nuclear states of the double-beta decay. We use the like-particle QRPA after the closure approximation is applied to the nuclear matrix elements. The overlap is calculated rigorously by making use of the explicit equation of the QRPA ground state. The formulation of the overlap is shown, and a test calculation is performed. The effectiveness of the truncations used is shown.