Isospin mixing and the continuum coupling in weakly bound nuclei

TL;DR

This paper investigates how Coulomb-induced isospin breaking affects weakly-bound nuclei's structure and spectroscopic factors using the Gamow Shell Model, revealing partial isospin symmetry despite symmetry-breaking effects.

Contribution

It introduces a complex-energy Gamow Shell Model approach to study isospin mixing and continuum effects in weakly bound nuclei, highlighting structure variations within isobaric triplets.

Findings

Isobaric analog states' structure varies within the isotriplet.

Spectroscopic factors depend on energy in weakly bound systems.

Partial dynamical isospin symmetry persists despite Coulomb effects.

Abstract

The isospin breaking effects due to the Coulomb interaction in weakly-bound nuclei are studied using the Gamow Shell Model, a complex-energy configuration interaction approach which simultaneously takes into account many-body correlations between valence nucleons and continuum effects. We investigate the near-threshold behavior of one-nucleon spectroscopic factors and the structure of wave functions along an isomultiplet. Illustrative calculations are carried out for the T=1 isobaric triplet. By using a shell-model Hamiltonian consisting of an isoscalar nuclear interaction and the Coulomb term, we demonstrate that for weakly bound or unbound systems the structure of isobaric analog states varies within the isotriplet and impacts the energy dependence of spectroscopic factors. We discuss the partial dynamical isospin symmetry present in isospin-stretched systems, in spite of the Coulomb interaction that gives rise to large mirror symmetry breaking effects.