Zero sound in triplet-correlated superfluid neutron matter

TL;DR

This paper investigates the existence and properties of zero sound modes in triplet-correlated superfluid neutron matter, relevant for neutron star physics, revealing anisotropic behavior and temperature-dependent damping effects.

Contribution

It provides a theoretical analysis of zero sound in superfluid neutron matter with specific pairing, highlighting anisotropy and interaction effects not previously detailed.

Findings

Zero sound is anisotropic in superfluid neutron matter.

Zero sound experiences strong damping below a certain temperature.

The results are relevant for understanding neutron star interior dynamics.

Abstract

The linear response of a superfluid neutron liquid onto external vector field is studied for the case of $^{3}P_{2}-\,^{3}F_{2}$ pairing. The consideration is limited to the case when the wave-length of the perturbation is large as compared to the coherence length in the superfluid matter and the transferred energy is small in comparison with the gap amplitude. The obtained results are used to analyse the collisionless phonon-like excitations of the condensate of superfluid neutrons. In particular, we analyze the case of neutron condensation into the state with $m_{j}=0$ which is conventionally considered as the preferable one in the bulk matter of neutron stars. Zero sound (if it exists) is found to be anisotropic and undergoes strong decrement below some temperature threshold depending substantially on the intensity of Fermi-liquid interactions.