Precision computation of the strange quark's mass in quenched QCD

We determine the renormalization group invariant quark mass corresponding to the sum of the strange and the average light quark mass in the quenched approximation of QCD, using as essential input the mass of the K-mesons. In the continuum limit we find (M_s+M)/F_K=0.874(29), which includes systematic errors. Translating this nonperturbative result into the running quark masses in the MS-scheme at #mu#=2 GeV and using the quark mass ratios from chiral perturbation theory, we obtain anti m_s (2 GeV)=97(4) MeV. With the help of recent results by the CP-PACS Collaboration, we estimate that a 10% higher value would be obtained if one replaced F_K by the nucleon mass to set the scale. This is a typical ambiguity in the quenched approximation. (orig.)55 refs.SIGLEAvailable from TIB Hannover: RA 2999(99-075) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Low energy physics from the QCD Schroedinger functional

We review recent work by the ALPHA and UKQCD Collaborations where masses and matrix elements were computed in lattice QCD using Schroedinger functional boundary conditions and where the strange quark mass was determined in the quenched approximation. We emphasize the general concepts and our strategy for the computation of quark masses. (orig.)18 refs.SIGLEAvailable from TIB Hannover: RA 2999(99-134) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman