Magnetic aspects of QCD and compact stars

TL;DR

This paper explores the magnetic properties of quark matter, including ferromagnetic transitions and spin density waves, using quantum chromodynamics and Fermi liquid theory, with implications for understanding magnetic phenomena in compact stars.

Contribution

It introduces a detailed analysis of magnetic behavior in quark matter, incorporating screening effects and non-Fermi-liquid behavior, and discusses implications for compact star physics.

Findings

Critical density for ferromagnetism around nuclear density

Non-Fermi-liquid behavior in magnetic susceptibility due to transverse gluons

Magnetization oscillates as a spin density wave at moderate densities

Abstract

Magnetic properties of quark matter are discussed. The possibility of ferromagnetic transition is studied by using the one-gluon-exchange interaction. Magnetic susceptibility is evaluated within Landau Fermi liquid theory, and the important roles of the screening for the gluon propagation are elucidated. Static screening for the longitudinal gluons improves the infrared singularities, while the transverse gluons receive only dynamic screening. The latter property gives rise to a novel non-Fermi-liquid behaviour in the magnetic susceptibility. The critical density is estimated to be around the nuclear density and the Curie temperature several tens MeV. The spin density wave is also discussed at moderate densities, where chiral transition becomes important. Pseudoscalar condensate as well as scalar one takes a spatially non-uniform form in a chirally invariant way. Accordingly magnetization oscillates like spin density wave. These results should have some implications on compact star phenomena.