Empirical pairing gaps and neutron-proton correlations

TL;DR

This paper investigates neutron-proton correlations in atomic nuclei through mass relations, revealing similarities in $np$ pairing estimates for $N=Z$ nuclei and complexities for $N e Z$, using shell model analysis.

Contribution

It compares various mass relation formulas for $np$ pairing, highlighting their differences across nuclei with different neutron-proton ratios and analyzing their structural interrelations.

Findings

Similar $np$ pairing estimates for $N=Z$ nuclei across formulas

Significant differences in $np$ pairing estimates for $N e Z$ nuclei

Shell Model analysis provides insights into mass formula structures

Abstract

Analysis of various mass relations connected with neutron-proton correlations in atomic nuclei is carried out. On the example of $N = Z$ chain it is shown that for self-adjoint nuclei various formulas proposed in literature for $ np $ pairing energy estimations lead to similar results. Significant differences between the calculation methods arise when nuclei with $N \ne Z$ are considered, which allows to show the complexity of neutron-proton correlations in different types of atomic nuclei and to make some assumptions on the correspondence of a mass ratio to the real effect of $ np $ pairing. The Shell Model parametrization of binding energy makes it possible to arrive to additional conclusions on the structure of mass formulas and their interrelationships with one another.