The quark mass gap in a magnetic field

TL;DR

This paper investigates how strong magnetic fields influence the quark mass gap, revealing that it saturates at a finite value while the chiral condensate grows, impacting phase transitions and meson structures in QCD.

Contribution

It provides a detailed analysis of the quark mass gap behavior under intense magnetic fields, highlighting the decoupling of the gap from the magnetic field at high strengths and implications for QCD phase transitions.

Findings

Mass gap saturates at ~ Lambda_QCD for B -> infinity.

Chiral condensate grows linearly with |eB|.

Critical temperatures for chiral and deconfinement decrease with increasing B.

Abstract

A magnetic field and the resulting Landau degeneracy enhance the infrared contributions to the quark mass gap. The gap does not grow arbitrarily, however, for models of asymptotic free interactions. For B -> infinity, the magnetic field decouples from the dimensionally reduced self-consistent equations, so that the gap behaves as ~ Lambda_QCD (or less), instead of ~ |eB|^{1/2}. On the other hand, the number of participants to the chiral condensate keeps increasing as ~ |eB| so that |<\bar{\psi} \psi>| ~ |eB| Lambda_QCD. After the mass gap stops developing, nothing tempers the growth of screening effects as B -> infinity. These features are utilized to interpret the reduction of critical temperatures for the chiral and deconfinement at finite B, recently found on the lattice. The structures of mesons are analyzed and light mesons are identified. Applications for cold, dense quark matter are also briefly discussed.