Near-BPS Skyrmions: Non-shell configurations and Coulomb effects

TL;DR

This paper introduces a generalized Skyrme model with specific terms and potentials, producing analytical near-BPS solutions that incorporate Coulomb effects, resulting in binding energies closely matching experimental nuclear data.

Contribution

It presents a new generalized Skyrme model with analytical solutions and Coulomb effects, supporting the near-BPS Skyrmion description of nuclei.

Findings

Analytical BPS-type solutions with non-shell baryon density configurations.

Coulomb energy inclusion improves binding energy predictions.

Model parameters fitted to experimental data show remarkable agreement.

Abstract

The relatively small binding energy in nuclei suggests that they may be well represented by near-BPS Skyrmions since their mass is roughly proportional to the baryon number $A.$ For that purpose, we propose a generalization of the Skyrme model with terms up to order six in derivatives of the pion fields and treat the nonlinear $\sigma$ and Skyrme terms as small perturbations. For our special choice of mass term (or potential) $V$, we obtain well-behaved analytical BPS-type solutions with non-shell configurations for the baryon density, as opposed to the more complex shell-like configurations found in most extensions of the Skyrme model . Along with static and (iso)rotational energies, we add to the mass of the nuclei the often neglected Coulomb energy and isospin breaking term. Fitting the four model parameters, we find a remarkable agreement for the binding energy per nucleon $B/A$ with respect to experimental data. These results support the idea that nuclei could be near-BPS Skyrmions.