Two-loop corrections to the Λ parameters of one-plaquette actions

We calculate the relationship between the coupling constants of different SU(N) lattice actions in two-loop weak-coupling perturbation theory. We perform a complete calculation for arbitrary one-plaquette lattice actions using the background field method. Our final result is presented in analytic form. Numerical results are also given for various actions (Wilson, Manton, heat-kernel and mixed fundamental-adjoint). (orig.)