# Superfluid Gap in Neutron Matter from a Microscopic Effective Interaction

## TL;DR

This paper investigates the superfluid gap in neutron matter using an improved microscopic effective interaction that includes three-nucleon forces, providing insights relevant to neutron star crusts.

## Contribution

It introduces an enhanced CBF effective interaction incorporating three-nucleon forces to study neutron superfluidity in dense matter.

## Key findings

- Superfluid gap appears at densities 2e-4 to 0.1 times nuclear saturation density.
- Results are relevant for understanding neutron star inner crust properties.
- The study advances microscopic modeling of nuclear interactions in neutron-rich matter.

## Abstract

Correlated Basis Function (CBF) perturbation theory and the formalism of cluster expansions have been recently employed to obtain an effective interaction from a nuclear Hamiltonian strongly constrained by phenomenology. We report the results of a study of the superfluid gap in pure neutron matter, associated with the formation of Cooper pairs in the $^1S_0$ channel. The calculations have been carried out using an improved version of the CBF effective interaction, in which three-nucleon forces are taken into account using a microscopic model. Our results show that a non-vanishing superfluid gap develops at densities in the range $2 \times 10^{-4} \lesssim \rho/\rho_0 \lesssim 0.1 $, where $\rho_0 = 2.8 \times 10^{14}$ g cm$^{-3}$ is the equilibrium density of isospin-symmetric nuclear matter, corresponding mainly to the neutron star inner crust.