The strength of crystalline color superconductors

TL;DR

This paper investigates the shear modulus of crystalline color superconductors, revealing they are extremely rigid and superfluid, with potential implications for neutron star phenomena like pulsar glitches.

Contribution

It provides the first calculation of the shear modulus of crystalline color superconductors, showing they are significantly more rigid than neutron star crusts.

Findings

Shear modulus is 20 to 1000 times larger than neutron star crusts.

The phase exhibits both high rigidity and superfluidity.

Potential impact on understanding pulsar glitches.

Abstract

We present a study of the shear modulus of the crystalline color superconducting phase of quark matter, showing that this phase of dense, but not asymptotically dense, quark matter responds to shear stress as a very rigid solid. This phase is characterized by a gap parameter $\Delta$ that is periodically modulated in space and therefore spontaneously breaks translational invariance. We derive the effective action for the phonon fields that describe space- and time-dependent fluctuations of the crystal structure formed by $\Delta$, and obtain the shear modulus from the coefficients of the spatial derivative terms. Within a Ginzburg-Landau approximation, we find shear moduli which are 20 to 1000 times larger than those of neutron star crusts. This phase of matter is thus more rigid than any known material in the universe, but at the same time the crystalline color superconducting phase is also superfluid. These properties raise the possibility that the presence of this phase within neutron stars may have distinct implications for their phenomenology. For example, (some) pulsar glitches may originate in crystalline superconducting neutron star cores.