Correlator of Topological Charge Densities in Instanton Model in QCD

TL;DR

This paper uses the instanton model in QCD to analyze the correlator of topological charge densities, determining the eta'-meson coupling, eta-eta' mixing angle, and the correlator at high momenta, aligning with recent experimental data.

Contribution

It introduces a QCD sum rule approach within the instanton model to connect topological charge correlators with meson properties and proton spin structure.

Findings

Eta'-meson coupling constant matches recent experimental values.

Eta-eta' mixing angle consistent with chiral effective theory.

Calculated topological charge correlator at high momenta.

Abstract

The QCD sum rule for the correlator of topological charge densities and related to it longitudinal part of the correlator of singlet axial currents is considered in the framework of instanton model. The coupling constant of eta'-meson with the singlet axial current is determined. Its value appears to be in a good coincidence with the value determined recently from the connection of the part of proton spin, carried by u,d,s quarks, with the derivative of QCD topological susceptibility. From the same sum rule eta-eta' mixing angle is found in the framework of two mixing angles model. Its value is close to that found in the chiral effective theory. The correlator of topological charge densities at large momenta is calculated.