Magnetism in Dense Quark Matter

TL;DR

This paper reviews how external magnetic fields influence the phases and properties of cold, dense quark matter, with implications for the physics of compact stars, highlighting new magnetic phases and condensates.

Contribution

It introduces the magnetic CFL (MCFL) phase and other magnetic-induced phases in dense quark matter, expanding understanding of magnetic effects on color superconductivity.

Findings

Identification of magnetic CFL (MCFL) phase relevant at gap-scale fields.

Analysis of the equation of state for MCFL matter across various magnetic field strengths.

Discussion of magnetic effects on dense quark matter in the context of compact star physics.

Abstract

We review the mechanisms via which an external magnetic field can affect the ground state of cold and dense quark matter. In the absence of a magnetic field, at asymptotically high densities, cold quark matter is in the Color-Flavor-Locked (CFL) phase of color superconductivity characterized by three scales: the superconducting gap, the gluon Meissner mass, and the baryonic chemical potential. When an applied magnetic field becomes comparable with each of these scales, new phases and/or condensates may emerge. They include the magnetic CFL (MCFL) phase that becomes relevant for fields of the order of the gap scale; the paramagnetic CFL, important when the field is of the order of the Meissner mass, and a spin-one condensate associated to the magnetic moment of the Cooper pairs, significant at fields of the order of the chemical potential. We discuss the equation of state (EoS) of MCFL matter for a large range of field values and consider possible applications of the magnetic effects on dense quark matter to the astrophysics of compact stars.