Eta-Eta' mixing and the derivative of the topological susceptibility at zero momentum transfer

TL;DR

This paper evaluates the couplings of isosinglet axial-vector currents to Eta and Eta' mesons, assesses corrections to the Gell-Mann-Oakes-Renner relation, and calculates the derivative of the topological susceptibility considering instantons.

Contribution

It introduces a model-independent method using polynomial kernels to evaluate meson couplings and computes the topological susceptibility derivative with instanton effects.

Findings

Couplings of axial-vector currents to Eta and Eta' mesons determined.

Corrections to the Gell-Mann-Oakes-Renner relation quantified.

Derivative of topological susceptibility calculated with instanton contributions.

Abstract

The couplings of the isosinglet axial-vector currents to the Eta and Eta' mesons are evaluated in a stable, model independent way by use of polynomial kernels in dispersion integrals. The corrections to the Gell-Mann-Oakes-Renner relation in the isoscalar channel are deduced. The derivative of the topological susceptibility at the origin is calculated taking into account instantons and instanton screening.