Topological and magnetic properties of the QCD vacuum probed by overlap fermions

TL;DR

This paper investigates the topological and magnetic characteristics of the QCD vacuum using overlap fermions in lattice gauge theory, revealing inhomogeneous topological charge distributions, magnetic effects on chirality, and properties like magnetization and conductivity.

Contribution

It provides new insights into the local CP-odd and magnetic properties of the QCD vacuum, including the structure of chirality distribution and magnetic catalysis effects.

Findings

Chirality localized on low-dimensional defects in uncooled configurations

Magnetic field enhances local chirality fluctuations

QCD vacuum exhibits magnetization and increased electric conductivity in strong magnetic fields

Abstract

We study some of the local CP-odd and magnetic properties of the non-Abelian vacuum with use of overlap fermions within the quenched lattice gauge theory. Among these properties are the following: inhomogeneous spatial distribution of the topological charge density (chirality for massless fermions) in SU(2) gluodynamics (for uncooled gauge configurations the chirality is localized on low-dimensional defects with d=2..3, while a sequence of cooling steps gives rise to four-dimensional instantons and hence a four-dimensional structure of the chirality distribution); finite local fluctuations of the chirality growing with the strength of an external magnetic field; magnetization and susceptibility of the QCD vacuum in SU(3) theory; magnetic catalysis of the chiral symmetry breaking, and the electric conductivity of the QCD vacuum in strong magnetic fields.