Can cold quark matter be solid?

TL;DR

This paper explores the possibility that cold quark matter in compact stars could exist as a solid state due to quark clustering, challenging the conventional view of color superconductivity.

Contribution

It proposes that cold quark matter may form a solid state through quark clustering, providing an alternative to the standard color superconductivity scenario.

Findings

Quarks are dressed and tend to cluster at realistic densities.

Cold quark matter could be in a solid state if interaction energy dominates thermal energy.

Solid quark matter may explain phenomena in pulsar-like compact stars.

Abstract

The state of cold quark matter really challenges both astrophysicists and particle physicists, even many-body physicists. It is conventionally suggested that BCS-like color superconductivity occurs in cold quark matter; however, other scenarios with a ground state rather than of Fermi gas could still be possible. It is addressed that quarks are dressed and clustering in cold quark matter at realistic baryon densities of compact stars, since a weakly coupling treatment of the interaction between constituent quarks would not be reliable. Cold quark matter is conjectured to be in a solid state if thermal kinematic energy is much lower than the interaction energy of quark clusters, and such a state could be relevant to different manifestations of pulsar-like compact stars.