– 1 – PRODUCTION AND DECAY OF b - FLAVORED HADRONS

In 1997 we celebrated the 20th anniversary of the discovery of the b quark. What started out as a bump in the dimuon invariant mass spectrum has turned into the exciting field of heavy flavor physics. Weak decays of heavy quarks provide access to fundamental parameters of the Standard Model, in particular the weak mixing angles of the Cabibbo-Kobayashi-Maskawa matrix. There is great hope that experiments with B mesons may lead to the first precise determination of the fourth CKM parameter, the complex phase. While the underlying decay of the heavy quark is governed by the weak interaction, it is the strong force that is responsible for the formation of the hadrons that are observed by experimenters. Although this complicates the extraction of the Standard Model parameters from the experimental data it also means that decays of B mesons provide an important laboratory to test our understanding of the strong interaction. New results that were added to this edition fall into two categories. Arguably the most exciting development since the last edition of this review is the progress in b-quark decays beyond the tree level. Gluonic penguin decays such as B → K − π + have been measured for the first time providing us with new opportunities to search for physics beyond the Standard Model and/or to probe the phase structure of the CKM matrix. At tree level, i.e. for b → c transitions, the CLEO collaboration used a sample of more than 6 million B decays to update branching fractions for many exclusive hadronic decay channels. New results on semileptonic decays have been reported by CLEO and the LEP collaborations. Lifetime measurements improved steadily and now have reached a precision of a few percent. Heavy flavor physics is a very dynamic field and in this brief review it is impossible to do justice to all recent theoretical and experimental developments. I will highlight a few new results