Magnetic Oscillations in Dense Cold Quark Matter with Four-Fermion Interactions

TL;DR

This paper explores the complex phase structure of dense cold quark matter under magnetic fields, revealing multiple phase transitions, Landau level effects, and both standard and non-standard magnetic oscillations in thermodynamic and dynamical quantities.

Contribution

It introduces a detailed analysis of magnetic oscillations in dense quark matter, including non-periodic oscillations with H-dependent frequencies, extending understanding of Landau level effects.

Findings

Existence of infinitely many phases with Landau levels

Standard van Alphen-de Haas oscillations in massless case

Non-standard, non-periodic oscillations in massive case

Abstract

The phase structures of Nambu-Jona-Lasinio models with one or two flavours have been investigated at non-zero values of $\mu$ and $H$, where $H$ is an external magnetic field and $\mu$ is the chemical potential. In the phase portraits of both models there arise infinitely many massless chirally symmetric phases, as well as massive ones with spontaneously broken chiral invariance, reflecting the existence of infinitely many Landau levels. Phase transitions of first and second orders and a lot of tricritical points have been shown to exist in phase diagrams. In the massless case, such a phase structure leads unavoidably to the standard van Alphen-de Haas magnetic oscillations of some thermodynamical quantities, including magnetization, pressure and particle density. In the massive case we have found an oscillating behaviour not only for thermodynamical quantities, but also for a dynamical quantity as the quark mass. Besides, in this case we have non-standard, i.e. non-periodic, magnetic oscillations, since the frequency of oscillations is an $H$-dependent quantity.