Extracting the $\eta^\prime$ meson mass from gluonic correlators in lattice QCD

TL;DR

This paper presents a lattice QCD method using gluonic operators and Wilson flow to accurately extract the eta-prime meson mass, overcoming challenges of noisy disconnected diagrams.

Contribution

It introduces a novel gluonic operator approach combined with Wilson flow to improve eta-prime mass extraction in lattice QCD simulations.

Findings

Successful extraction of eta-prime mass across multiple lattice spacings

Estimation of continuum and large volume limits

Reduction of noise and cancellation issues in disconnected diagrams

Abstract

Calculation of the eta-prime meson mass is a notoriously difficult problem, as it requires evaluation of the disconnected diagram which is costly and noisy. In this work, we use a gluonic operator to extract the eta-prime state after smearing the link variables through the Wilson flow. With this choice, one can avoid a large cancellation of pion contribution between the connected and disconnected diagrams. We obtain the eta-prime meson mass on lattices with three different lattice spacings and two physical volumes, which allow us to estimate its continuum and large volume limits.