Quark Condensate and Effective Action from Dyson--Schwinger Equations

TL;DR

This paper derives the QCD quark condensate and quark virtuality using Dyson-Schwinger equations, and explores their impact on the non-perturbative Euler-Heisenberg Lagrangian in external fields.

Contribution

It introduces a non-local extension of the quark condensate and calculates its effects within Dyson-Schwinger formalism, providing new insights into non-perturbative QCD.

Findings

Calculated the quark condensate from unquenched Dyson-Schwinger equations.

Determined the quark virtuality associated with the condensate.

Derived the non-perturbative contribution to the Euler-Heisenberg Lagrangian.

Abstract

We obtain the QCD quark condensate from consideration of unquenched quark dynamics in Dyson-Schwinger gluon vacuum. We consider the non-local extension of the condensate and determine the quark virtuality. We also obtain the condensate-driven contribution of the non-perturbative QCD to Euler--Heisenberg Lagrangian of QED in external electromagnetic fields.