Rigid triaxiality has the SU(3) symmetry: $^{166}$Er as an example

TL;DR

This paper demonstrates that the SU(3) interacting boson model accurately describes the triaxial deformation and collective properties of $^{166}$Er, supporting its interpretation as a triaxial nucleus.

Contribution

It extends the SU(3) IBM by including higher-order interactions to effectively model triaxial shapes in $^{166}$Er.

Findings

Calculated energy spectra match experimental data.

$B(E2)$ transition strengths agree with measurements.

Quadrupole moments support triaxial deformation.

Abstract

The emergence of triaxiality in the low-lying collective bands of $^{166}$Er is systematically explored within the SU3-IBM. In this framework, SU(3) higher-order interactions are included, which enable the descriptions of various quadrupole deformations. The triaxiality of $^{166}$Er is described with a triaxiality angle $\gamma=9.7^{\circ}$. In addition, the calculated energy spectra, $B(E2)$ transition strengths, and quadrupole moments show excellent agreement with experimental data. These results provide further evidence supporting the SU(3) triaxial interpretation of $^{166}$Er and confirm its triaxial deformation rather than the prolate shape.