Constructing local composite operators for glueball states from a confining Gribov propagator

The construction of BRST invariant local operators with the quantum numbers of the lightest glueball states, $J^{PC}= 0^{++}, 2^{++}, 0^{-+}$, is worked out by making use of an Euclidean confining renormalizable gauge theory. The correlation functions of these operators are evaluated by employing a confining gluon propagator of the Gribov type and shown to display a spectral representation with positive spectral densities. An attempt to provide a first qualitative analysis of the ratios of the masses of the lightest glueballs is also discussed