Topological Susceptibility on Dynamical Staggered Fermion Configurations

TL;DR

This paper investigates how different lattice fermion actions affect the measurement of topological susceptibility in QCD, highlighting the importance of lattice spacing and fermion action improvements for accurate results.

Contribution

It demonstrates that fat link fermions better reproduce chiral behavior of topological susceptibility at larger lattice spacings compared to thin link staggered fermions.

Findings

Thin link staggered fermions require small lattice spacing (~0.1fm) to show expected chiral behavior.

Fat link fermions reproduce theoretical expectations even at larger lattice spacings (~0.17fm).

Improved flavor symmetry in fat link actions enhances the accuracy of topological susceptibility measurements.

Abstract

The topological susceptibility is one of the few physical quantities that directly measure the properties of the QCD vacuum. Chiral perturbation theory predicts that in the small quark mass limit the topological susceptibility depends quadratically on the pion mass, approaching zero in the chiral limit. Lattice calculations have difficulty reproducing this behavior. In this paper we study the topological susceptibility on dynamical staggered fermion configurations. Our results indicate that the lattice spacing has to be small, around a~0.1fm for thin link staggered fermion actions to show the expected chiral behavior. Our preliminary result indicates that fat link fermions, on the other hand, reproduce the theoretical expectations even on lattices with a~0.17fm. We argue that this is due to the improved flavor symmetry of fat link fermionic actions.