Self-consistent Gaussian model of nonperturbative QCD vacuum

Abstract

We show that the minimal Gaussian model of nonlocal vacuum quark and quark-gluon condensates in QCD generates the non-transversity of vector current correlators. We suggest the improved Gaussian model of the nonperturbative QCD vacuum, which respects QCD equations of motion and minimizes the revealed gauge-invariance breakdown. We obtain the refined values of pion distribution amplitude (DA) conformal moments using the improved QCD vacuum model and construct the allowed region for Gegenbauer coefficients a_2 and a_4 of the pion DA.

Comments: 15 pages, 7 figures, english version