Systematic study of nuclear matrix elements in neutrinoless double-beta decay with a beyond mean-field covariant density functional theory

TL;DR

This study systematically evaluates nuclear matrix elements for neutrinoless double-beta decay using an advanced relativistic density functional approach, improving agreement with previous models and simplifying calculations.

Contribution

It introduces a comprehensive relativistic framework that includes dynamic effects and full transition operators, enhancing the accuracy of NME calculations for neutrinoless double-beta decay.

Findings

Better agreement with non-relativistic calculations for most nuclei.

Total NMEs can be approximated by the axial-vector term.

Significant reduction in computational effort.

Abstract

We report a systematic study of nuclear matrix elements (NMEs) in neutrinoless double-beta decays with a state-of-the-art beyond mean-field covariant density functional theory. The dynamic effects of particle-number and angular-momentum conservations as well as quadrupole shape fluctuations are taken into account with projections and generator coordinate method for both initial and final nuclei. The full relativistic transition operator is adopted to calculate the NMEs. The present systematic studies show that in most of the cases there is a much better agreement with the previous non-relativistic calculation based on the Gogny force than in the case of the nucleus $^{150}$Nd found in Song et al. [Phys. Rev. C 90, 054309 (2014)]. In particular, we find that the total NMEs can be well approximated by the pure axial-vector coupling term with a considerable reduction of the computational effort.