Triaxiality in the interacting boson model

TL;DR

This paper investigates signature splitting in gamma-vibrational bands of various isotopes using the interacting boson model, highlighting the importance of three-body interactions and finding no evidence for stable triaxial ground states.

Contribution

It demonstrates that including three-body interactions between d bosons improves the IBM's description of signature splitting in gamma bands.

Findings

Three-body interactions improve model accuracy

No evidence for stable triaxial ground states

Model reproduces experimental signature splitting better

Abstract

The signature splitting of the $\gamma$-vibrational band of several Ru, Pd, Xe, Ba, Os and Pt isotopes is analyzed in the framework of the interacting boson model (IBM). The nuclei studied are close to the $\gamma$-unstable SO(6) limit of the IBM and have well-known $\gamma$ bands. It is shown that in most nuclei the signature splitting is better reproduced by the inclusion of a three-body interaction between the $d$ bosons. In none of the nuclei evidence for a stable, triaxial ground-state shape is found.