VARIATIONAL APPROACH TO THE QCD WAVE FUNCTIONAL - DYNAMICAL MASS GENERATION AND CONFINEMENT

We perform a variational calculation in the SU(N) Yang-Mills theory in 3 + 1 dimensions. Our trial variational states are explicitly gauge i nvariant, and reduce to simple Gaussian states in the sere coupling li mit. Our main result is that the energy is minimized for the value of the variational parameter away from the perturbative value. The best v ariational state is therefore characterised by a dynamically generated mass scale M. This scale is related to the perturbative scale Lambda( QCD) by the relation alpha(QCD)(M) = (pi/4N). Taking the one-loop QCD beta function and Lambda(QCD) = 150 MeV we find (for N = 3) the vacuum condensate (alpha/pi)[F-2] = 0.008 GeV4.