A nonperturbative calculation of basic chiral QCD parameters within zero modes enhancement model of the QCD vacuum

Abstract

Basic chiral QCD parameters (the pion decay constant, the quark and gluon condensates, the dynamically generated quark mass, etc.) as well as the vacuum energy density (up to the sign, by definition, the bag constant) have been calculated from first principles within a recently proposed zero modes enhancement (ZME) model of the true QCD vacuum. This is based on the solution to the Schwinger-Dyson (SD) equation for the quark propagator in the infrared (IR) domain. There are only two independent quantities (free parameters) by means of which calculations must be done. Our unique input data was chosen to be the pion decay constant in the chiral limit as given by the chiral perturbation theory at the hadronic level (CHPTh). In order to analyse our numerical results we set a scale in two different ways. In both cases we obtain almost the same numerical results for all chiral QCD parameters. Phenomenological estimates of these quantities, as well as of the vacuum energy density, are in good agreement with our numerical results.