Short- and long-distance QCD effects in B-meson decays

Various exclusive and inclusive decays of B mesons are studied, at present, with dedicated experiments at ``B factories''. In order to compete with the experimental accuracy, we need a reliable theoretical framework to compute strong interaction effects in a hadronic environment. I discuss how the separation of (perturbatively calculable) short-distance QCD effects from (non-perturbative) long-distance phenomena helps to obtain precise theoretical predictions.Comment: Invited talk given at Hadrons 03, Aschaffenburg, Germany; 10 pages, 6 figures, uses aipproc.cl

Renormalization Group Evolution of Flavour Invariants

The fermion spectrum in the Standard Model (SM) exhibits hierarchical structures between the eigenvalues of the Yukawa matrices which determine the fermion masses, as well as certain hierarchical patterns in the mixing matrix that describes weak transitions between different fermion generations. A basis-independent description of the SM flavour structure can be given in terms of a complete set of flavour invariants. In this paper, we construct a convenient set of such invariants, and discuss the general form of the renormalization-group equations. We also discuss the simplifications that arise from exploiting hierarchies in Yukwawa couplings and mixings which are present in the SM or its minimal-flavour violating extensions.Comment: 27 pages, 3 figure

Is there a non-Standard-Model contribution in non-leptonic b -> s decays?

Precision measurements of branching fractions and CP asymmetries in non-leptonic b -> s decays reveal certain "puzzles" when compared with Standard Model expectations based on a global fit of the CKM triangle and general theoretical expectations. Without reference to a particular model, we investigate to what extent the (small) discrepancies observed in (B -> J/psi K), (B -> phi K) and (B -> K pi) may constrain new physics in (b -> s q qbar) operators. In particular, we compare on a quantitative level the relative impact of different quark flavours q=c,s,u,d.Comment: 25 pages, 7 figures, some references added, brief discussion of B -> J/psi \pi include