A Fresh Look at the B Semileptonic Branching Ratio and Beauty Lifetimes

Abstract

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.

Comments: 14 pages, 5 figures appended, to appear in the Proceedings of Les Rencontres de Physique de la Vallee d'Aoste, Results and Perspectives in Particle Physics (La Thuile, Italy, March 1996)