Glueball spectrum of SU(3) lattice gauge theory by plaquette expansion

By casting the Hamiltonian of pure SU(3) in 3+1 space-time dimensions into approximate tri-diagonal form we study the glueball spectrum of the system. In particular we obtain estimates for the ground state energy density, the string tension sigma, and the masses of the lowest lying 0(++), 1(+-) and 2(++) glueballs. These initial calculations lead to estimates of various mass ratios in general agreement with other studies of the spectrum.