Multi-reference many-body perturbation theory for nuclei II -- Ab initio study of neon isotopes via PGCM and IM-NCSM calculations

TL;DR

This paper presents an ab initio study of neon isotopes using PGCM and IM-NCSM methods, exploring their structure and correlations, with a focus on shape deformation and the island of inversion phenomena.

Contribution

It introduces a combined application of PGCM and IM-NCSM methods with chiral EFT Hamiltonians to study complex nuclear phenomena in neon isotopes.

Findings

PGCM effectively captures static correlations and low-lying spectra.

IM-NCSM provides quasi-exact solutions for nuclear states.

Systematic uncertainties are evaluated using chiral EFT Hamiltonians.

Abstract

The neon isotopic chain displays a rich phenomenology, ranging from clustering in the ground-state of the self-conjugate doubly open-shell stable $^{20}$Ne isotope to the physics of the island of inversion around the neutron-rich $^{30}$Ne isotope. This second (i.e. Paper II) of the present series proposes an extensive ab initio study of neon isotopes based on two complementary many-body methods, i.e. the quasi-exact in-medium no-core shell model (IM-NCSM) and the projected generator coordinate method (PGCM) that is ideally suited to capturing strong static correlations associated with shape deformation and fluctuations. Calculations employ a state-of-the-art generation of chiral effective field theory Hamiltonians and evaluate the associated systematic uncertainties. In spite of missing so-called dynamical correlations, which can be added via the multi-reference perturbation theory proposed in the first paper (i.e. Paper I) of the present series, the PGCM is shown to be a suitable method to tackle the low-lying spectroscopy of complex nuclei. Still, describing the physics of the island of inversion constitutes a challenge that seems to require the inclusion of dynamical correlations. This is addressed in the third paper (i.e. Paper III) of the present series.