Screening masses towards chiral limit

TL;DR

This study investigates the potential restoration of the $U_A(1)$ symmetry in QCD by analyzing scalar and pseudo-scalar screening masses across different pion masses using lattice QCD simulations.

Contribution

It provides the first continuum-extrapolated results of scalar and pseudo-scalar screening masses near the chiral limit in (2+1)-flavor QCD with HISQ discretization.

Findings

Preliminary continuum-extrapolated masses presented.

Differences in susceptibilities show non-trivial structure at $N_\tau=8$.

Results suggest possible signals of $U_A(1)$ restoration.

Abstract

A possible effective restoration of the anomalous $U_A(1)$ symmetry would have a non-trivial effect on the global phase diagram of QCD. In this work we investigate the effective restoration of the $U_A(1)$ through the calculation of scalar and pseudo-scalar screening masses and corresponding susceptibilities, for physical and lower than physical pion masses. Calculations have been performed in (2+1)-flavor HISQ discretization scheme with a physical value of the strange quark mass. Preliminary calculations of the continuum extrapolated scalar and pseudo-scalar masses are presented, based on lattices with three different temporal extent. Non-trivial structure of the difference between scalar and pseudo-scalar susceptibilites are discussed for $N_\tau=8$ lattices.