$\eta^\prime$ meson mass from topological charge density correlator in QCD

TL;DR

This study calculates the eta prime meson mass using a gluonic topological charge density correlator in lattice QCD, achieving results consistent with experiments at lower computational cost.

Contribution

It introduces a gluonic correlator method with Yang-Mills gradient flow to determine the eta prime mass more efficiently and cleanly than traditional quark-based approaches.

Findings

Mass in the chiral and continuum limit matches experimental value

Gluonic correlator avoids pion contamination

Lower numerical cost compared to conventional methods

Abstract

The flavor-singlet component of the eta prime meson is related to the topological structure of the SU(3) gauge field through the chiral anomaly. We perform a 2+1-flavor lattice QCD calculation and demonstrate that the two-point function of a gluonically defined topological charge density after a short Yang-Mills gradient flow contains the propagation of the eta prime meson, by showing that its mass in the chiral and continuum limit is consistent with the experimental value. The gluonic correlator does not suffer from the contamination of the pion contribution, and the clean signal is obtained at significantly lower numerical cost compared to the conventional method with the quark bilinear operators.