The mean square radius of the neutron distribution in the relativistic and non-relativistic mean field models

TL;DR

This paper compares relativistic and non-relativistic mean field models to understand differences in neutron distribution radii, highlighting the role of effective mass and potential strength constrained by fundamental theorems.

Contribution

It clarifies the origin of the radius difference by linking it to effective mass and potential strength, constrained by the Hugenholtz-Van Hove theorem.

Findings

Non-relativistic models predict smaller neutron radii by about 0.1 fm.

The difference arises from the product of effective mass and potential strength.

Neutron skin thickness depends on nucleon effective mass, not just symmetry potential.

Abstract

It is investigated why the root mean square radius of the point neutron distribution is smaller by about 0.1 fm in non-relativistic mean field models than in relativistic ones. The difference is shown to stem from the different values of the product of the effective mass and the strength of the one-body potential in the two frameworks. The values of those quantities are constrained by the Hugenholtz-Van Hove theorem. The neutron skin is not a simple function of the symmetry potential, but depends on the nucleon effective mass.