Semiclassical description of chiral geometry in triaxial nuclei

TL;DR

This paper develops a semiclassical model to describe chiral symmetry breaking in triaxial nuclei, revealing how two minima in the energy landscape emerge at a critical angular momentum, leading to chiral doublet bands.

Contribution

It introduces a semiclassical approach using a time-dependent variational principle to analyze chiral symmetry breaking in triaxial nuclei with quasiparticles.

Findings

Classical energy function shows two minima beyond a critical angular momentum.

Quantized energy levels form a double well potential, explaining chiral partner bands.

Model successfully describes chiral doublet bands in $^{134}$Pr.

Abstract

A triaxial particle-rotor Hamiltonian for three mutually perpendicular angular momentum vectors corresponding to two high-$j$ quasiparticles and the rotation of a triaxial collective core, is treated within a time-dependent variational principle. The resulting classical energy function is used to investigate the rotational dynamics of the system. It is found that the classical energy function exhibits two minima starting from a critical angular momentum value which depends on the single-particle configuration and the asymmetry measure $\gamma$. The emergence of the two minima is attributed to the breaking of the chiral symmetry. Quantizing the energy function for a given angular momentum, one obtains a Schr\"{o}dinger equation with a coordinate dependent mass term for a symmetrical potential which changes from a single to a double well shape as the angular momentum pass the critical value. The energies of the chiral partner bands for a given angular momentum are then given by the lowest two eigenvalues. The procedure is exemplified for maximal triaxiality and two $h_{11/2}$ quasiparticles, with the results used for the description of the chiral doublet bands in $^{134}$Pr.