Deformation and the Nuclear Matrix Elements of the Neutrinoless Double Beta Decay

TL;DR

This paper reviews current methods for calculating nuclear matrix elements of neutrinoless double beta decay, highlighting how nuclear deformation affects these calculations and comparing different theoretical approaches.

Contribution

It provides a comparative analysis of NME calculations using the Interacting Shell Model and QRPA, emphasizing the impact of nuclear deformation on NME values.

Findings

NME values decrease with increasing deformation difference between parent and daughter nuclei.

Deformation effects significantly influence the accuracy of NME calculations.

Comparison shows differences between ISM and QRPA approaches in predicting NME.

Abstract

In this talk I will review the "state of the art" of the calculations of the nuclear matrix elements (NME) of the neutrinoless double beta decays for the nuclei 48Ca, 76Ge, 82Se, 124Sn, 128Te, 130Te and 136Xe in the framework of the Interacting Shell Model (ISM), and compare them with the NME's obtained using the Quasi-particle RPA approach (QRPA). I will also discuss the effect of the competition between the pairing and quadrupole correlations in the value of these NME's. In particular I will show that, as the difference in deformation between parent and grand daughter grows, the NME's of both the neutrinoless and the two neutrino modes decrease rapidly.