The QCD topological susceptibility at high temperatures via staggered fermions spectral projectors

TL;DR

This paper presents lattice QCD results for the topological susceptibility at high temperatures using spectral projectors on staggered fermions, aiming to improve accuracy over traditional gluonic methods for axion phenomenology.

Contribution

It introduces a spectral projector method for calculating topological susceptibility in high-temperature QCD with staggered fermions, reducing lattice artifacts compared to standard approaches.

Findings

Spectral projector method yields more reliable susceptibility estimates at high temperatures.

Comparison shows spectral and gluonic methods differ due to lattice artifacts.

Results support spectral projectors as a promising tool for axion-related QCD studies.

Abstract

The QCD topological observables are essential inputs to obtain theoretical predictions about axion phenomenology, which are of utmost importance for current and future experimental searches for this particle. Among them, we focus on the topological susceptibility, related to the axion mass. We present lattice results for the topological susceptibility in QCD at high temperatures obtained by discretizing this observable via spectral projectors on eigenmodes of the staggered Dirac operator, and we compare them with those obtained with the standard gluonic definition. The adoption of the spectral discretization is motivated by the large lattice artifacts affecting the standard gluonic susceptibility, related to the choice of non-chiral fermions in the lattice action.