Proton-neutron pairing and binding energies of nuclei close to N=Z line

TL;DR

This paper investigates how proton-neutron pairing influences the binding energies of nuclei near the N=Z line using a mean-field approach with a quartet condensation model that conserves particle number and isospin.

Contribution

It introduces a self-consistent Skyrme-HF+QCM method to analyze the effects of isovector and isoscalar pairing on nuclear binding energies near N=Z, highlighting the limited impact of isoscalar pairing.

Findings

Binding energies are minimally affected by isoscalar pairing.

Off-diagonal matrix elements of the pairing force are less attractive for isoscalar pairing.

Competition between isoscalar and isovector pairing channels influences energy contributions.

Abstract

We analyse the contribution of isovector and isoscalar proton-neutron pairing to the binding energies of even-even nuclei with $N-Z=0,2,4$ and atomic mass $20 < A <100$. The binding energies are calculated in the mean-field approach by coupling a Skyrme-type functional to an isovector-isoscalar pairing force of zero range. The latter is treated in the framework of quartet condensation model (QCM), which conserves exactly the particle number and the isospin. The interdependence of pairing and deformation is taken into account by performing self-consistent Skyrme-HF+QCM calculations in the intrinsic system. It is shown that the binding energies are not changing much when the isoscalar pairing is switched on. This fact is related to the off-diagonal matrix elements of the pairing force, which is less attractive for the isoscalar force, and to the competition between the isoscalar and isovector pairing channels.