Axial U(1) symmetry at finite temperature with M\"obius domain-wall fermions

TL;DR

This study examines the restoration of axial U(1) symmetry at finite temperature in two-flavor QCD using M"obius domain-wall fermions, revealing suppression of symmetry breaking effects above the chiral transition.

Contribution

It demonstrates that reweighting to overlap fermions suppresses U(1)_A breaking effects at high temperature, providing insights into symmetry restoration in QCD.

Findings

Suppression of U(1)_A breaking above the chiral transition temperature.

Zero and near-zero modes dominate the symmetry-breaking signal.

Reweighting to overlap fermions reduces U(1)_A breaking effects.

Abstract

We investigate the axial $U(1)$ symmetry restoration at finite temperature in two flavor QCD. We employ the M\"obius domain-wall formalism that is designed to achieve good chiral symmetry. We show the measurements of a difference of meson susceptibilities, sensitive to the $U(1)_A$ symmetry breaking. The signal is dominated by zero and near-zero modes. By reweighting the measure to that of overlap fermions we find a suppression of the $U(1)_A$ breaking effects above the chiral transition temperature.