Quark mixing and CP violation - the CKM matrix

Abstract

I present the status of the elements and parameters of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and summarise the related theoretical progress since "Lepton-Photon 2003". One finds |V_{us}| = 0.2227 +/- 0.0017 from K and tau decays and |V_{cb}| = (41.6 +/- 0.5) * 10^{-3} from inclusive semileptonic B decays. The unitarity triangle can now be determined from tree-level quantities alone and the result agrees well with the global fit including flavour-changing neutral current (FCNC) processes, which are sensitive to new physics. From the global fit one finds the three CKM angles theta_{12}=12.9 +/- 0.1 degrees, theta_{23}= 2.38 +/- 0.03 degrees and theta_{13}= 0.223 +/- 0.007 degrees in the standard PDG convention. The CP phase equals delta_{13} = gamma = (58.8 +5.3/-5.8) degrees at 1 sigma CL and gamma=(58.8 +11.2/-15.4) degrees at 2 sigma CL. A major progress are first results from fully unquenched lattice QCD computations for the hadronic quantities entering the UT fit. I further present the calculation of three-loop QCD corrections to the charm contribution in K+ -> pi+ nu nu-bar decays, which removes the last relevant theoretical uncertainty from the K -> pi nu nu-bar system. Finally I discuss mixing-induced CP asymmetries in b -> s q-bar q penguin decays, whose naive average is below its Standard Model value by 3 sigma.