Number-conserving theory of nuclear pairing gaps: a global assessment

TL;DR

This paper develops a number-conserving nuclear pairing gap theory using a Skyrme mean-field approach and Monte Carlo methods, improving the fit to experimental data by accurately treating pairing correlations.

Contribution

It introduces a numerically exact, number-conserving method for nuclear pairing gaps and refines the pairing interaction strength across a large set of nuclei.

Findings

Significant reduction in rms error of pairing gaps to 0.12 MeV.

Monte Carlo method enables practical solutions in large model spaces.

Improved agreement with experimental pairing gaps despite mean-field limitations.

Abstract

We study odd-even mass staggering of nuclei, also called pairing gaps, using a Skyrme self-consistent mean-field theory and a numerically exact treatment of the pairing Hamiltonian. We find that the configuration-space Monte Carlo method proposed by Cerf and Martin offers a practical computational procedure to carry out the numerical solutions in large-dimensional model spaces. Refitting the global strength of the pairing interaction for 443 neutron pairing gaps in our number-conserving treatment, we find the correction to the pairing correlation energies and pairing gaps to have rms values of 0.6 MeV and 0.12 MeV, respectively. The exact treatment provides a significant improvement in the fit to experimental gaps, although it is partially masked by a larger rms error due to deficiencies in other aspects of the theory such as the mean-field energy functional.