Multiple chiral doublets in four-$j$ shells particle rotor model: five possible chiral doublets in $^{136}_{~60}$Nd$_{76}$

TL;DR

This paper develops a particle rotor model to explain multiple chiral doublets in the nucleus $^{136}$Nd, successfully reproducing experimental data and identifying it as the first even-even nucleus with such multiple chiral doublets, setting a new record.

Contribution

The study introduces a novel particle rotor model coupling four $j$-shell nucleons to a triaxial core, revealing multiple chiral doublets in an even-even nucleus for the first time.

Findings

Successfully reproduces experimental spectra and transition ratios.

Identifies $^{136}$Nd as the first even-even nucleus with multiple chiral doublets.

Establishes multiple chiral doublets as a new phenomenon in nuclear chirality.

Abstract

A particle rotor model, which couples nucleons in four single-$j$ shells to a triaxial rotor core, is developed to investigate the five pairs of nearly degenerate doublet bands recently reported in the even-even nucleus $^{136}$Nd. The experimental energy spectra and available $B(M1)/B(E2)$ values are successfully reproduced. The angular momentum geometries of the valence nucleons and the core support the chiral rotation interpretations not only for the previously reported chiral doublet, but also for the other four candidates. Hence, $^{136}$Nd is the first even-even candidate nucleus in which the multiple chiral doublets exist. Five pairs of chiral doublet bands in a single nucleus is also a new record in the study of nuclear chirality.