Single Particle Levels and ββ-Decay Matrix Elements in The Interacting Boson Model

J Barea,J Kotila

doi:10.1088/1742-6596/1056/1/012003

Abstract

Recently a new method to calculate the occupancies of single particle levels in atomic nuclei was developed in the context of the microscopic interacting boson model, in which neutron and proton degrees of freedom are treated explicitly (IBM-2). The energies of the single particle levels constitute a very important input for the calculation of the occupancies in this method, and further they play important role in the calculation of double beta decay nuclear matrix elements. Here we discuss how the 0νββ, 0νhββ, and 2νββ-decay nuclear matrix elements (NMEs) are affected when the energies of single particle levels are changed.

Highlights

The question of whether neutrinos are Majorana or Dirac particles, and of what are their masses and phases in the mixing matrix, remains one of the most important in physics today
Concomitant with the neutrinoless modes, there is the process allowed by the standard model, 2νββ, which has been observed in several nuclei
We have calculated the occupancies of the single particle levels in order to satisfy a twofold goal: to asses the goodness of the single particle energies and check the reliability of the used wave functions. Both tests are important in the case of nuclei involved in double beta decay, as they affect the evaluation of the nuclear matrix elements (NMEs) and their reliability [2]

Summary

Introduction

The question of whether neutrinos are Majorana or Dirac particles, and of what are their masses and phases in the mixing matrix, remains one of the most important in physics today. A direct measurement of the average mass can be obtained from the observation of the neutrinoless double beta decay, 0νββ. Where G0ν is a phase space factor, M0ν the nuclear matrix element and f (mi, Uei) contains physics beyond the standard model through the masses mi and mixing matrix elements Uei of neutrino species.

Results

Conclusion