Rolling Skyrmions and the Nuclear Spin-Orbit Force

TL;DR

This paper calculates the nuclear spin-orbit coupling using the Skyrme model, introducing a new method that applies to single nucleons orbiting large nuclei, and finds sign corrections non-perturbatively.

Contribution

It develops a novel approach to compute the spin-orbit force in the Skyrme model for realistic nuclear systems.

Findings

Second-order perturbation yields incorrect sign of spin-orbit coupling.

Non-perturbative effects recover the correct sign as pion-nucleon interaction strength increases.

Method applicable to single nucleons around large nuclei.

Abstract

We compute the nuclear spin-orbit coupling from the Skyrme model. Previous attempts to do this were based on the product ansatz, and as such were limited to a system of two well-separated nuclei. Our calculation utilises a new method, and is applicable to the phenomenologically important situation of a single nucleon orbiting a large nucleus. We find that, to second order in perturbation theory, the coefficient of the spin-orbit coupling induced by pion field interactions has the wrong sign, but as the strength of the pion-nucleon interactions increases the correct sign is recovered non-perturbatively.