Coexistence of quartets and pairs in even-even $N>Z$ nuclei

TL;DR

This paper investigates the structure of ground states in even-even N>Z nuclei, proposing a model combining quartets for N=Z subsystems and pair condensates for excess neutrons, with analysis of its accuracy in sd and pf shells.

Contribution

It introduces a novel approach to model ground states as a product of quartets and pairs, enhancing understanding of nuclear structure in N>Z nuclei.

Findings

The quartet-pair model accurately describes ground states in sd and pf shells.

The approach captures the coexistence of quartets and pairs in nuclear structure.

The model provides a new perspective on nucleon interactions in N>Z nuclei.

Abstract

We analyse the structure of the ground states of even-even $N>Z$ nuclei with nucleons moving in the same major shell and interacting via realistic two-body forces of shell-model type. We express the ground states of these nuclei as a product of a quartet term, which represents the $N = Z$ subsystem, and a pair condensate built with the excess neutrons. The accuracy of this approximation is discussed for nuclei with valence nucleons in the $sd$ and $pf$ major shells.