  The gauge invariant two-point correlator for the gluon field strength tensor
in analysed by means of the QCD sum rule method. To this end, we make use of a
relation of this correlator to a two-point function for a quark-gluon hybrid in
the limit of the quark mass going to infinity. From the sum rules a relation
between the gluon correlation length and the gluon condensate is obtained.
