Goldstone modes in the neutron star core

TL;DR

This paper develops a theoretical framework for Goldstone bosons in neutron star cores, focusing on their interactions, transport properties, and potential roles in neutron star seismology.

Contribution

It introduces a detailed theory of angulons and superfluid phonons in dense nucleonic matter, highlighting their distinct transport behaviors and interactions in neutron star cores.

Findings

Angulons have large mean free paths and weak coupling to electrons.

Superfluid phonons couple strongly to electrons and have shorter mean free paths.

Goldstone modes influence neutron star seismology and magnetic field interactions.

Abstract

We formulate a theory of Goldstone bosons and their interactions in the superfluid and superconducting phase of dense nucleonic matter at densities of relevance to the neutron star core. For typical neutron star temperatures in the range T = 10^6 to 10^9 K, the Goldstone mode associated with rotational symmetry, called angulons, couple weakly to each other and to electrons. Consequently, these modes have anomalously large mean free paths and can contribute to both diffusive and ballistic transport of heat and momentum. In contrast, the two Goldstone bosons associated with density oscillations of the neutron and electron + proton fluids, called superfluid phonons, mix and couple strongly to electrons. They have shorter mean free paths, and their contribution to transport is negligible. Long-wavelength superfluid phonons and angulons can play a role in neutron star seismology, and lead to interesting phenomenology as angulons couple to magnetic fields and have anisotropic dispersion relations.