Chiral condensate, susceptibilities, critical coupling and indices in QED$_4$

TL;DR

This paper investigates the critical behavior of chiral condensates and susceptibilities in noncompact QED4 using lattice simulations, revealing discrepancies with existing theoretical predictions.

Contribution

It introduces a method to measure chiral susceptibilities directly in the chiral limit, avoiding mass extrapolation, and provides new insights into the critical behavior in QED4.

Findings

Chiral susceptibilities measured in the Coulomb phase of QED4.

Critical couplings determined from simulations.

Disagreement with scalar Mean Field theory predictions.

Abstract

We measure chiral susceptibilities in the Coulomb phase of noncompact QED$_4$ in $8^4, 10^4$ and $12^4$ lattices. The MFA approach allows simulations in the chiral limit which are therefore free from arbitrary mass extrapolations. Using the critical couplings extracted from these calculations, we study the critical behaviour of the chiral condensate, which we find in disagreement with the predictions of logarithmically improved scalar Mean Field theory.