Neutron matter: The unitary limit and its far-reaching impact

TL;DR

This paper investigates low-density neutron matter near the unitary limit, constructing potentials with infinite scattering length, and discusses implications for nuclear physics and neutron-rich systems.

Contribution

It introduces realistic chiral effective field theory potentials near the unitary limit for neutron matter analysis.

Findings

Neutron matter behavior close to the unitary limit is characterized.

The relevance of unitarity constraints for symmetry energy is emphasized.

Predictions are based on chiral effective field theory at N3LO.

Abstract

We explore low-density neutron matter and its behavior in proximity to the unitary limit. To that end, we construct unitary nucleon-nucleon potentials with infinite 1S0 neutron-neutron scattering lengths. We discuss the Berstch parameter in relation to results from ultra-cold atomic gases. Unitarity as a constraint for neutron matter and the symmetry energy has been discussed in the literature. We revisit some of those arguments and emphasize the relevance of keeping a firm link with low-energy nuclear physics for robust predictions of neutron-rich systems. Our predictions are obtained from realistic few-nucleon forces based on chiral effective field theory at N3LO.