Preasymptotic effects in beauty decays

Abstract

Large preasymptotic effects in beauty decays have been found using heavy-quark and SU(3) symmetry, as well as experimental data on charmed hyperons. Contrary to rather uniform beauty-meson lifetimes, a much larger spread of beauty-baryon lifetimes is predicted. However, it is highly unlikely that, theoretically, the $\tau ({\Lambda }_b)/\tau (B_d^0)$ ratio, which at present deviates more than $1\sigma$ from the experimental result, can be lowered below 0.9.

Comments: 6 pages, talk given by B. Melic at The 3rd International Conference on B Physics and CP Violation, Taipei, Taiwan, December 3-7, 1999, to appear in the Proceedings, two figures added