Vacuum Structure in QCD with Quark and Gluon Condensates

Abstract

We consider here the vacuum structure in QCD with both quark and gluon condensates and a variational ansatz for the ground state. The method is nonperturbative using only equal time algebra for the field operators. We then find that a constrained energy minimisation of the Hamiltonian leads to a QCD vacuum with both quark and gluon condensates for $α_s > α_c=0.62$. Pion decay constant and the charge radius of the pion seem to fix the QCD coupling constant $α_s$ as 1.28. The approach opens up possibilities of relating the mysterious vacuum structure with common place hadronic properties.