Chiral magnetization of non-Abelian vacuum: a lattice study

TL;DR

This lattice study investigates the chiral magnetization of non-Abelian vacuum in Yang-Mills theory, revealing linear behavior in weak fields and nonlinear saturation in strong fields, with implications for understanding QCD vacuum properties.

Contribution

The paper provides the first lattice calculation of chiral magnetization and susceptibility in non-Abelian vacuum, including temperature effects and nonlinear magnetic responses.

Findings

Magnetization is proportional to magnetic field in weak fields.

Chiral susceptibility times condensate is approximately 46 MeV.

Magnetization exhibits nonlinear behavior described by an inverse tangent function.

Abstract

The chiral magnetization properties of cold and hot vacua are studied using quenched simulations in lattice Yang-Mills theory. In weak external magnetic fields the magnetization is proportional to the first power of the magnetic field. We evaluate numerically the coefficient of the proportionality (the chiral susceptibility) using near-zero eigenmodes of overlap fermions. We found that the product of the chiral susceptibility and the chiral condensate equals to 46(3) MeV. This value is very close to the phenomenological value of 50 MeV. In strong fields the magnetization is a nonlinear function of the applied magnetic field. We find that the nonlinear features of the magnetization are well described by an inverse tangent function. The magnetization is weakly sensitive to temperature in the confinement phase.