Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

TL;DR

This study uses nuclear density functional theory and particle-core coupling to explore octupole correlations in neutron-rich odd-mass barium isotopes, revealing that octupole deformation influences higher energy states rather than ground states.

Contribution

It introduces a microscopic, self-consistent model combining boson-fermion interactions with deformation constraints to accurately reproduce spectroscopic data of barium isotopes.

Findings

Model reproduces experimental spectra of Ba isotopes.

Octupole deformation is relevant only at higher excitation energies.

Ground state structures are not significantly affected by octupole deformation.

Abstract

Octupole deformation and the relevant spectroscopic properties of neutron-rich odd-mass barium isotopes are investigated in a theoretical framework based on nuclear density functional theory and the particle-core coupling scheme. The interacting-boson Hamiltonian that describes the octupole-deformed even-even core nucleus, as well as the single-particle energies and occupation probabilities of an unpaired nucleon, are completely determined by microscopic axially-symmetric $(\beta_{2},\beta_{3})$-deformation constrained self-consistent mean-field calculations for a specific choice of the energy density functional and pairing interaction. A boson-fermion interaction that involves both quadrupole and octupole degrees of freedom is introduced, and their strength parameters are determined to reproduce selected spectroscopic data for the odd-mass nuclei. The model reproduces recent experimental results both for the even-even and odd-mass Ba isotopes. In particular, for $^{145,147}$Ba our results indicate, in agreement with recent data, that octupole deformation does not determine the structure of the lowest states in the vicinity of the ground state, and only becomes relevant at higher excitation energies.