Spontaneous Breaking of Rotational Symmetry in Rotating Solitons - a Toy Model of Excited Nucleons with High Angular Momentum

TL;DR

This paper investigates how rotational symmetry spontaneously breaks in rotating baby Skyrme models, revealing that high angular momentum causes less symmetric, lower-energy configurations, which may shed light on deformed excited nucleons.

Contribution

It demonstrates the occurrence of spontaneous symmetry breaking in rotating baby Skyrme models and proposes a mechanism explaining its presence, unlike in the standard model.

Findings

Symmetry breaking occurs above a critical angular momentum.

Deformed configurations have lower energy at high angular momentum.

Results may help understand non-spherical excited nucleons.

Abstract

We study the phenomenon of spontaneous breaking of rotational symmetry (SBRS) in the rotating solutions of two types of baby Skyrme models. In the first the domain is a two-sphere and in the other, the Skyrmions are confined to the interior of a unit disk. Numerical full-field results show that when the angular momentum of the Skyrmions increases above a certain critical value, the rotational symmetry of the solutions is broken and the minimal energy configurations become less symmetric. We propose a possible mechanism as to why SBRS is present in the rotating solutions of these models, while it is not observed in the `usual' baby Skyrme model. Our results might be relevant for a qualitative understanding of the non-spherical deformation of excited nucleons with high orbital angular momentum.