Gluonic correlation functions and Bethe-Salpeter amplitudes are calculated in an instanton-based model of the QCD vacuum. We consider both the pure gauge case and the situation for real QCD with two light quark flavors. We show that instantons lead to a strong attractive force in the $J^{\mathrm{PC}}{=0\mathrm{}}^{++}$ channel, which results in the scalar glueball being much smaller than other glueballs. In the $0^{-+}$ channel the corresponding force is repulsive, and in the $2^{++}$ case it is absent. The resulting correlators, masses, coupling constants, and wave functions are compared to the results of lattice simulations.

• Received 10 November 1994

DOI:https://doi.org/10.1103/PhysRevLett.75.1707