Anisotropy in Magnetized Quark Matter in the Chiral Limit

TL;DR

This paper explores how strong magnetic fields influence the thermodynamic, magnetic, and phase transition properties of cold quark matter, revealing anisotropic pressures, oscillatory behaviors, and phase transition shifts within a nonlocal NJL model.

Contribution

It provides a detailed analysis of anisotropic pressures, oscillations, and phase transitions in magnetized quark matter using a nonlocal NJL model in the chiral limit, highlighting new magnetic effects.

Findings

Pressure anisotropy between parallel and perpendicular directions.

Oscillations in quark number density and magnetization due to Landau levels.

Transition to chirally restored phases at lower chemical potentials for higher magnetic fields.

Abstract

We investigate the behavior of cold quark matter under strong magnetic fields in the frame of a nonlocal NJL model in the chiral limit. Our analysis focuses on deconfinement, chiral symmetry restoration, and the anisotropy in pressure induced by the external magnetic field. For $eB\lesssim 0.07~ \text{GeV}^2$, the critical chemical potential remains largely insensitive to the magnetic field, whereas at higher field strengths, transitions to chirally restored phases occur at progressively lower chemical potentials. The parallel and perpendicular pressures, respect to the magnetic field, exhibit distinct behaviors, reflecting the anisotropic nature of the system. Oscillations in the quark number density, driven by the de Haas van Alphen effect, reflect the quantized behavior of quarks in a magnetic field. Similarly, the magnetization displays oscillatory behavior, driven by the sequential filling of Landau levels. At lower external magnetic field strengths, contributions from orbital angular momentum and the population of higher Landau levels further modulate these oscillations. These results provide deeper insights into the thermodynamic and magnetic properties of quark matter under strong magnetic fields, with implications for astrophysical studies.