Running sums for $2\nu\beta\beta$-decay matrix elements within the QRPA with account for deformation

TL;DR

This paper calculates the running sums for $2 uetaeta$-decay matrix elements in deformed nuclei using QRPA with realistic interactions, highlighting the impact of model parameters on the decay process and resonance contributions.

Contribution

It introduces a QRPA approach with deformation and realistic interactions to analyze $2 uetaeta$-decay, emphasizing the role of the $g_{pp}$ parameter and resonance effects.

Findings

The $g_{pp}$ parameter significantly affects the behavior of running sums.

Negative contributions from the giant Gamow-Teller resonance are substantial.

Results align with previous studies on resonance contributions to decay.

Abstract

The $2\nu\beta\beta$-decay running sums for $^{76}$Ge and $^{150}$Nd nuclei are calculated within a QRPA approach with account for deformation. A realistic nucleon-nucleon residual interaction based on the Brueckner G matrix (for the Bonn CD force) is used. The influence of different model parameters on the functional behavior of the running sums is studied. It is found that the parameter $g_{pp}$ renormalizing the G matrix in the QRPA particle-particle channel is responsible for a qualitative change in behavior of the running sums at higher excitation energies. For realistic values of $g_{pp}$ a significant negative contribution to the total $2\nu\beta\beta$-decay matrix element is found to come from the energy region of the giant Gamow-Teller resonance. This behavior agrees with the results of other authors.