2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198431We compute the Schroedinger functional (SF) for the case of lattice QCD with Wilson fermions (with and without SW improvement) at two-loop order in lattice perturbation theory. This allows us to extract the three-loop beta-function in the SF-scheme. These results are required to compute the running coupling, the Lambda-parameter and quark masses by finite size techniques with negligible systematic errors. In addition our results enable the implementation of two-loop O(a) improvement in SF-simulations.30 pages, numerical changes in eqs.(A.9), (A.10), (5.6), (5.9), (5.12) due to the revision of hep-lat/9801007v2 (Christou et al.)High Energy Physics - Latticetext