Proton-proton 1S0 pairing in neutron star

TL;DR

This paper investigates how medium effects influence proton pairing in neutron stars, revealing that these effects significantly reduce the superfluid gap and alter the understanding of proton superfluidity's role in neutron-star cooling.

Contribution

It provides a detailed analysis of medium polarization effects on proton pairing, showing their impact on the superfluid gap and implications for neutron-star physics.

Findings

Medium polarization effects reduce the proton pairing gap.

Vertex corrections are attractive but have limited quantitative impact.

The superfluid phase scenario in neutron stars is significantly reshaped.

Abstract

The onset of 1S0 proton spin-singlet pairing in neutron-star matter is studied in the framework of the BCS theory including medium polarization effects. The strong three-body coupling of the diproton pairs with the dense neutron environment and the self-energy effects severely reduce the gap magnitude, so to reshape the scenario of the proton superfluid phase inside the star. The vertex corrections due to the medium polarization are attractive in all isospin-asymmetry range at low density and tend to favor the pairing in that channel. However quantitative estimates of their effect on the energy gap do not give significant changes. Implications of the new scenario on the role of pairing in neutron-star cooling is briefly discussed.