Anatomy of octupole correlations in $^{96}$Zr with a symmetry-restored multidimensionally-constrained covariant density functional theory

TL;DR

This study uses advanced density functional theory calculations to reveal that octupole deformation in $^{96}$Zr's ground state is energetically favored after symmetry restoration, highlighting the importance of symmetry breaking and restoration in nuclear structure modeling.

Contribution

It introduces a projection-after-variation approach within a multidimensionally-constrained relativistic framework to accurately describe octupole correlations in $^{96}$Zr, surpassing pure mean-field models.

Findings

Octupole deformed shape is energetically favored after symmetry restoration.

Pure mean-field calculations cannot reproduce the observed octupole deformation.

Shell structure competition influences complex nuclear shapes in $^{96}$Zr.

Abstract

A recent analysis based on the STAR measurement in relativistic heavy-ion collision experiments provides evidence of octupole correlation in the ground state of $^{96}$Zr, the description of which presents a challenge to nuclear structure models. In this work, we perform projection-after-variation calculations for $^{96}$Zr based on a multidimensionally-constrained relativistic Hartree-Bogoliubov model. Our results show that an octupole deformed shape is favored in energy after symmetry restoration, and this phenomenon cannot be reproduced in the pure mean-field calculations. These complex structures originate from the competition among various shell structures in this mass region. Our results suggest that the allowance of symmetry breaking at the mean-field level and the restoration of broken symmetries are essential elements for understanding the structure of $^{96}$Zr in density functional theories.