The Kohn-Luttinger Effect in Dense Matter and its Implications for Neutron Stars

TL;DR

This paper explores how the Kohn-Luttinger effect, involving repulsive interactions, can induce p-wave pairing in dense neutron and quark matter, with implications for neutron star physics.

Contribution

It demonstrates that repulsive short-range interactions in dense matter can lead to p-wave Cooper pairing, especially in neutron stars, extending the understanding of pairing mechanisms under extreme conditions.

Findings

Repulsive interactions can induce p-wave pairing in neutron matter.

Pairing gaps in neutrons can range from 10 keV to 10 MeV.

Induced interactions in quark matter are too weak for significant pairing.

Abstract

Repulsive short-range interactions can induce p-wave attraction between fermions in dense matter and lead to Cooper pairing at the Fermi surface. We investigate this phenomenon, well-known as the Kohn-Luttinger effect in condensed matter physics, in dense matter with strong short-range repulsive interactions. We find that repulsive interactions required to stabilize massive neutron stars can induce p-wave pairing in neutron and quark matter. When massive vector bosons mediate the interaction between fermions, the induced interaction favors Cooper pairing in the 3P2 channel. For the typical strength of the interaction favored by massive neutron stars, the associated pairing gaps in neutrons can be in the range of 10 keV to 10 MeV. Strong and attractive spin-orbit and tensor forces between neutrons can result in repulsive induced interactions that greatly suppress the 3P2 pairing gap in neutron matter. In quark matter, the induced interaction is too small to result in pairing gaps of phenomenological relevance.