Application of the Coupled Cluster Method to a Hamiltonian Lattice Field Theory

The coupled cluster method has been applied to the eigenvalue problem lattice Hamiltonian QCD (without quarks) for SU(2) gauge fields in two space dimensions. Using a recently presented new formulation and the truncation prescription of Guo et al. we were able to compute the ground state and the lowest $0^+$-glueball mass up to the sixth order of the coupled cluster expansion. The results show evidence for a ``scaling window'' (i.e. good convergence and constance of dimensionless quantities) around $\beta=4/g^2 \approx 3$. A comparison of our results to those of other methods is presented.