The mass of odd-odd nuclei in microscopic mass models

TL;DR

This paper evaluates the performance of recent microscopic nuclear mass models in predicting the binding energies of odd-odd nuclei and discusses potential improvements to address identified deficiencies.

Contribution

It analyzes the shortcomings of current models in accounting for odd-odd nuclei binding energies and explores ways to enhance their accuracy.

Findings

Current models fail to fully capture odd-odd nuclei contributions.

Analysis of mass difference formulas reveals specific deficiencies.

Proposals for future model improvements are discussed.

Abstract

Accurate estimates of the binding energy of nuclei far from stability that cannot be produced in the laboratory are crucial to our understanding of nuclear processes in astrophysical scenarios. Models based on energy density functionals have shown that they are capable of reproducing all known masses with root-mean-square error better than 800 keV, while retaining a firm microscopic foundation. However, it was recently pointed out in [M. Hukkanen et al., arXiv:2210.10674] that the recent BSkG1 model fails to account for a contribution to the binding energy that is specific to odd-odd nuclei, and which can be studied by using appropriate mass difference formulas. We analyse here the (lacking) performance of three recent microscopic mass models with respect to such formulas and examine possibilities to remedy this deficiency in the future.