Topological structure of chiral QCD vacuum

TL;DR

This paper develops an analytical framework to calculate key QCD vacuum properties like gluon condensate and topological susceptibility, combining models of quantum zero modes and instantons, and validates results against phenomenological data.

Contribution

It introduces a combined approach using ZME and RILM models to evaluate the QCD vacuum's topological features and mass spectrum in the chiral limit.

Findings

Good agreement with phenomenological values of topological susceptibility

Accurate estimation of the $ ext{η'}$ meson mass in the chiral limit

Validation of the QCD vacuum model against experimental data

Abstract

Using the trace anomaly relation, low-energy theorem and Witten-Veneziano formula, we have developed an analytical formalism which allows one to calculate the gluon condensate, the topological susceptibility and the mass of the $\eta'$ meson in the chiral limit as functions of the non-perturbative vacuum energy density. It is used for numerical evaluation of the chiral QCD topology within the QCD vacuum model consisting mainly of the quantum component given by the recently proposed zero modes enhancement (ZME) model and the classical component given by the the random instanton liquid model (RILM). We sum up both contributions into the total, nonperturbative vacuum energy density. A very good agreement with the phenomenological values of the topological susceptibility, the mass of the $\eta'$ meson in the chiral limit and the gluon condensate has been obtained. This puts the above mentioned QCD vacuum model on a firm phenomenological ground.