Singlet axial-vector coupling constant of the nucleon in QCD without instantons

TL;DR

This paper calculates the nucleon's singlet axial-vector coupling constant using QCD current correlators without instanton effects, aligning well with experimental and theoretical values.

Contribution

It introduces a method to determine the nucleon's singlet axial-vector coupling constant without relying on instanton effects, using current-current correlators.

Findings

The calculated coupling constant matches experimental values.

The method avoids instanton contributions, simplifying analysis.

Results are consistent with existing QCD and experimental data.

Abstract

We have analyzed axial-vector current-current correlation functions between one-nucleon states to calculate the singlet axial-vector coupling constant of the nucleon. The octet-octet and the octet-singlet current correlators, investigated in this work, do not require any use of instanton effects. The QCD and hadronic parameters used for the evaluation of correlators have been varied by (10 - 20)%. The value of the singlet axial-vector coupling constant of the nucleon obtained from this analysis is consistent with its current determination from experiments and QCD theory.