Analysis of the intermediate-state contributions to neutrinoless double beta-minus decays

TL;DR

This paper analyzes the nuclear matrix elements of neutrinoless double beta-minus decays, focusing on intermediate states and using the pnQRPA model with realistic interactions to improve understanding of decay mechanisms.

Contribution

It provides a detailed multipole decomposition of NMEs in neutrinoless double beta-minus decays using an advanced pnQRPA approach with realistic interactions and symmetry restoration.

Findings

Detailed multipole contributions identified

Enhanced accuracy in NME calculations

Insights into decay mechanisms

Abstract

A comprehensive analysis of the structure of the nuclear matrix elements (NMEs) of neutrinoless double beta-minus decays to the 0^+ ground and first excited states is performed in terms of the contributing multipole states in the intermediate nuclei of neutrinoless double beta-minus transitions. We concentrate on the transitions mediated by the light (l-NMEs) Majorana neutrinos. As nuclear model we use the proton-neutron quasiparticle random-phase approximation (pnQRPA) with a realistic two-nucleon interaction based on the Bonn one-boson-exchange G matrix. In the computations we include the appropriate short-range correlations, nucleon form factors, higher-order nucleonic weak currents and restore the isospin symmetry by the isoscalar-isovector decomposition of the particle-particle proton-neutron interaction parameter g_{pp}.