# Quartet correlations in N=Z nuclei induced by realistic two-body interactions

## TL;DR

This paper extends variational quartet models to general two-body interactions to study alpha-like correlations in N=Z nuclei, showing that ground states can be well described by a condensate of identical quartets, especially in $^{32}$S.

## Contribution

The paper introduces extended quartet models for general two-body interactions and demonstrates their effectiveness in describing correlations in N=Z nuclei, particularly $^{32}$S.

## Key findings

- Ground states of N=Z nuclei are well described by alpha-like quartet condensates.
- High overlap between quartet condensate and shell model wave functions in $^{32}$S.
- Limited correspondence between excited states of quartet models and shell model eigenstates.

## Abstract

Two variational quartet models previously employed in a treatment of pairing forces are extended to the case of a general two-body interaction. One model approximates the nuclear states as a condensate of identical quartets with angular momentum $J=0$ and isospin $T=0$ while the other let these quartets to be all different from each other. With these models we investigate the role of alpha-like quartet correlations both in the ground state and in the lowest $J=0$, $T=0$ excited states of even-even $N=Z$ nuclei in the $sd$-shell. We show that the ground state correlations of these nuclei can be described to a good extent in terms of a condensate of alpha-like quartets. This turns out to be especially the case for the nucleus $^{32}$S for which the overlap between this condensate and the shell model wave function is found close to one. In the same nucleus, a similar overlap is found also in the case of the first excited $0^+$ state. No clear correspondence is observed instead between the second excited states of the quartet models and the shell model eigenstates in all the cases examined.