Pairing in high-density neutron matter including short- and long-range correlations

TL;DR

This paper improves the calculation of neutron pairing gaps by including short- and long-range correlations, which significantly affect the gaps and are relevant for understanding neutron star cooling.

Contribution

It introduces a method to incorporate both short- and long-range correlations into neutron matter pairing gap calculations, advancing beyond traditional BCS approaches.

Findings

Short-range correlations substantially suppress pairing gaps.

Long-range correlations provide a small correction to the gaps.

Results are relevant for neutron-star cooling models.

Abstract

Pairing gaps in neutron matter need to be computed in a wide range of densities to address open questions in neutron star phenomenology. Traditionally, the Bardeen-Cooper-Schrieffer approach has been used to compute gaps from bare nucleon-nucleon interactions. Here, we incorporate the influence of short- and long-range correlations in the pairing gaps. Short-range correlations are treated including the appropriate fragmentation of single-particle states, and substantially suppress the gaps. Long-range correlations dress the pairing interaction via density and spin modes, and provide a relatively small correction. We use different interactions, some with three-body forces, as a starting point to control for any systematic effects. Results are relevant for neutron-star cooling scenarios, in particular in view of the recent observational data on Cassiopeia A.