Quark Condensate and Effective Action from Dyson--Schwinger Equations

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.

9 pages, 10 figures