Cold neutrons trapped in external fields

TL;DR

This paper uses advanced computational methods to study inhomogeneous neutron matter under external fields, revealing significant differences from traditional models in nuclear physics and neutron star crust predictions.

Contribution

It provides new microscopic calculations that constrain and improve the understanding of neutron-rich matter and nuclear energy density functionals.

Findings

Isovector gradient terms are more repulsive than in current models.

Spin-orbit and pairing forces are weaker than traditionally assumed.

Differences impact predictions for neutron star crusts and heavy nuclei.

Abstract

The properties of inhomogeneous neutron matter are crucial to the physics of neutron-rich nuclei and the crust of neutron stars. Advances in computational techniques now allow us to accurately determine the binding energies and densities of many neutrons interacting via realistic microscopic interactions and confined in external fields. We perform calculations for different external fields and across several shells to place important constraints on inhomogeneous neutron matter, and hence the large isospin limit of the nuclear energy density functionals that are used to predict properties of heavy nuclei and neutron star crusts. We find important differences between microscopic calculations and current density functionals; in particular the isovector gradient terms are significantly more repulsive than in traditional models, and the spin-orbit and pairing forces are comparatively weaker.