Realistic shell model description of beta decay

Angela Gargano,Luca De Angelis,Luigi Coraggio,Tokuro Fukui,Nunzio Itaco,N Arsenyev,I Rogov,A Vdovin,T Shneidman,A Bezbakh

doi:10.1051/epjconf/201819402007

Abstract

In this paper, we extend our previous realistic shell-model study of Gamow-Teller strengths and double-β decay properties for nuclei around 132Sn to lighter mass nuclei. The effective shell-model Hamiltonian and transition operators are microscopically derived by way of many-body perturbation theory, without resorting to empirical parameters. Our main aim is to further check the reliability of our approach and verify its stability in other mass regions. Calculated energy spectra as well as electric-quadrupole and β-decay properties are presented for 76Ge and 82Se and compared with the experimental data, together with some results for 130Te and 136Xe already reported in our previous paper. Finally, some preliminary results of nuclear matrix elements responsible for the neutrinoless double beta decay, calculated by using the bare operator, are shown.

Highlights

The neutrinoless double beta (0νββ) decay provides a major opportunity to address relevant questions about the mass and the nature of neutrinos
We have presented the results of realistic shell model (SM) calculations for 76Ge, 82Se, 130Te, and 136Xe, with special attention to their GT decay properties
The SM Hamiltonian, including both the two-body matrix elements and single-particle energies, as well as the transition operators are calculated by way of the many-body perturbation theory, starting from a low-momentum interaction derived from the highprecision CD-Bonn free NN potential

Summary

Introduction

A valuable tool to address this problem is given by the realistic shell model (SM) [8, 9] Within this approach, the SM Hamiltonian and the transition operators are derived from a realistic free nuclear potential by way of manybody perturbation theory on the same footing. The SM Hamiltonian and the transition operators are derived from a realistic free nuclear potential by way of manybody perturbation theory on the same footing In this way, one can account for renormalization effects induced by missing correlations in the nuclear wave functions as resulting from truncations of the Hilbert space. The effective SM Hamiltonian and transition operators are derived within the timedependent perturbation theory [14], including diagrams up to the third order Within this approach we have computed the 0νββ decay NMEs by employing the bare operators for all the four nuclei under investigation. A summary and some concluding remarks are given in the last section

Theoretical framework

Results

Summary and Perspectives