Beyond relativistic mean-field approach for nuclear octupole excitations

TL;DR

This paper advances nuclear structure modeling by incorporating symmetry restoration and shape fluctuations into relativistic energy density functional calculations, providing a detailed microscopic understanding of octupole excitations in 224Ra.

Contribution

It introduces a beyond-mean-field approach combining symmetry projections and shape fluctuations into relativistic density functional theory for the first time.

Findings

Clarifies the origin of spin-dependent parity splitting in low-spin states.

Shows the connection between octupole shape stabilization and parity-doublet states.

Demonstrates the gradual shape transition from positive to negative parity states.

Abstract

We report the first beyond-mean-field study of low-lying parity-doublet states in 224Ra by extending the multireference relativistic energy density functional method to include dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We clarify full microscopically that the origin of spin-dependent parity splitting in low-spin states is related to the octupole shape stabilization of positive-parity states, the dominated shapes of which drift gradually to that of negative-parity ones.