Existence of exotic torus configuration in high-spin excited states of $^{40}$Ca

TL;DR

This study predicts a stable exotic torus-shaped high-spin state in $^{40}$Ca at 60 ħ angular momentum, indicating a circulating current and broken time-reversal symmetry in such nuclear configurations.

Contribution

First demonstration of a stable torus configuration in high-spin $^{40}$Ca using a 3D cranked Skyrme Hartree-Fock approach, revealing new exotic nuclear shapes.

Findings

Stable torus state at J=60 ħ found across various Skyrme interactions.

The state involves aligned nucleons with specific orbital angular momenta.

Emergence of circulating current breaking time-reversal symmetry in high-spin state.

Abstract

We investigate the possibility of the existence of the exotic torus configuration in the high-spin excited states of $^{40}$Ca. We here consider the spin alignments about the symmetry axis. To this end, we use a three-dimensional cranked Skyrme Hartree-Fock method and search for stable single-particle configurations. We find one stable state with the torus configuration at the total angular momentum $J=$ 60 $\hbar$ and an excitation energy of about 170 MeV in all calculations using various Skyrme interactions. The total angular momentum J=60 $\hbar$ consists of aligned 12 nucleons with the orbital angular momenta $\Lambda=+4$, +5, and +6 for spin up-down neutrons and protons. The obtained results strongly suggest that a macroscopic amount of circulating current breaking the time-reversal symmetry emerges in the high-spin excited state of $^{40}$Ca.