Understanding Xe isotopes near $A=130$ through the prolate-oblate shape phase transition

TL;DR

This paper introduces an algebraic model within the interacting boson framework to describe shape phase transitions in Xe isotopes near A=130, revealing novel gamma-soft modes and explaining experimental quadrupole moments.

Contribution

It presents a new algebraic scheme that captures the prolate-oblate shape phase transition and associated gamma-soft modes in Xe isotopes, enhancing understanding of nuclear shape dynamics.

Findings

Identification of gamma-soft modes near the critical point of the shape phase transition.

Explanation of nearly vanishing quadrupole moment in certain Xe isotopes.

Demonstration of the model's ability to reproduce experimental quadrupole moments.

Abstract

A simple algebraic scheme incorporating the prolate-oblate shape phase transition (SPT) is proposed within the framework of the interacting boson model to describe the quadrupole deformation features of Xe isotopes near $A=130$. The analysis demonstrates that novel $\gamma$-soft modes, characterized by the unusual quadrupole moments $Q(2_1^+)<0$ and $0<Q(2_2^+)\ll |Q(2_1^+)|$, can emerge near the critical point of this SPT. This finding is further applied to interpret the properties of low-lying states in the relevant Xe nuclei, particularly the experimentally observed nearly vanishing spectroscopic quadrupole moment $Q(2_2^+)$, thereby offering new insights into the structure of a $\gamma$-soft deformed nucleus.