B decays in the Standard Model - status and perspectives

These lectures review some of the progress made in the quantitative understanding of B decays. The emphasis here is on applications of QCD using perturbative and non-perturbative techniques. In some cases, however, phenomenological models must at present be invoked to make meaningful comparison with data. The resulting picture is consistent with the standard model (SM) and this agreement is quantified in terms of the branching ratios, mixing probabilities, and lifetimes which measure the charge current and effective flavour changing neutral current transitions involving B hadrons. This, in turn, enables a determination of five of the nine elements of the quark mixing matrix. We discuss several proposals on improving the precision on the parameters of this matrix in forthcoming experiments. Issues intimately related to the quark mixing matrix such as the profile of the unitarity triangle and CP-violating asymmetries in B decays are discussed. In particular, we emphasize the role of rare B decays and B0 - B0 mixings in testing the SM quantitatively and in searching for physics beyond the SM. (author)