Islands of shape coexistence in proxy-SU(3) symmetry and in covariant density functional theory

TL;DR

This paper predicts regions of shape coexistence in nuclei across the chart using proxy-SU(3) symmetry and covariant density functional theory, highlighting the role of shell effects and particle-hole excitations.

Contribution

It introduces a combined approach using proxy-SU(3) symmetry and covariant density functional theory to identify shape coexistence regions in nuclei.

Findings

Prediction of specific regions of shape coexistence on the nuclear chart.

Identification of islands where particle-hole excitations lead to shape coexistence.

Clarification of the role of magic number collapse and particle-hole excitations.

Abstract

Shape coexistence in even-even nuclei is observed when the ground state band of a nucleus is accompanied by another K=0 band at similar energy but with radically different structure. We attempt to predict regions of shape coexistence throughout the nuclear chart using the parameter-free proxy-SU(3) symmetry and standard covariant density functional theory. Within the proxy-SU(3) symmetry the interplay of shell model magic numbers, formed by the spin-orbit interaction, and the 3-dimensional isotropic harmonic oscillator magic numbers, leads to the prediction of specific horizontal and vertical stripes on the nuclear chart in which shape coexistence should be possible. Within covariant density functional theory, specific islands on the nuclear chart are found, in which particle-hole excitations leading to shape coexistence are observed. The role played by particle-hole excitations across magic numbers as well as the collapse of magic numbers as deformation sets in is clarified.