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

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 96Zr, the description of which presents a challenge to nuclear structure models. In this work, we perform projection-after-variation calculations for 96Zr 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 96Zr in density functional theories.