Topological susceptibility in staggered fermion chiral perturbation theory

TL;DR

This paper investigates how taste-breaking artifacts in staggered fermion formulations affect the topological susceptibility in lattice QCD, comparing theoretical estimates with numerical simulation results to understand scaling violations.

Contribution

It provides an estimate of taste-breaking effects on topological susceptibility and compares these with recent lattice simulation data.

Findings

Taste-breaking artifacts account for about half of the observed scaling violations.

The estimated taste-breaking contributions align with simulation results.

The study enhances understanding of discretization effects in staggered fermion approaches.

Abstract

The topological susceptibility of the vacuum in quantum chromodynamics has been simulated numerically using the Asqtad improved staggered fermion formalism. At nonzero lattice spacing the residual fermion doublers (fermion ``tastes'') in the staggered fermion formalism give contributions to the susceptibility that deviate from conventional continuum chiral perturbation theory. In this brief report we estimate the taste-breaking artifact and compare it with results of recent simulations, finding that it accounts for roughly half of the scaling violation.