A Fresh Look at the B Semileptonic Branching Ratio and Beauty Lifetimes
  We discuss two problems in the theory of heavy-quark decays: an understanding of the semileptonic branching ratio of $B$ mesons, and of the lifetime ratio $\tau(\Lambda_b)/\tau(B^0)$. We also present a model-independent study of spectator contributions to the lifetimes of beauty hadrons. 
Matthias Neubert (CERN)