Eur. Phys. J. A (2017) 53: 47
https://doi.org/10.1140/epja/i2017-12240-7

Regular Article - Theoretical Physics

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

¹ Istituto Nazionale di Fisica Nucleare - Sezione di Catania, Via S. Sofia 64, I-95123, Catania, Italy
² National Institute of Physics and Nuclear Engineering, 76900, Bucharest-Magurele, Romania

^* e-mail: sandulescu@theory.nipne.ro

Received: 21 November 2016
Accepted: 20 February 2017
Published online: 8 March 2017

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.