Theoretical status of the lifetime predictions: $(\Delta \Gamma /\Gamma {)}_{B_s},{\tau }_{B^{+}}/{\tau }_{B_d}$ and ${\tau }_{{\Lambda }_b}/{\tau }_{B_d}$

Abstract

We give a review of the theoretical status of the lifetime predictions in the standard model. In case of $(\Delta \Gamma /\Gamma {)}_{B_s}$ we are already in a rather advanced stage. We obtain $(\Delta \Gamma /\Gamma {)}_{B_s}=(9.3_{-4.6}^{+3.4})$. It seems to be difficult to improve these errors substantially. In addition now some experimental results are available. For ${\tau }_{B^{+}}/{\tau }_{B_d}$ and ${\tau }_{{\Lambda }_b}/{\tau }_{B_d}$ the theoretical status is much less advanced and the discrepancy between experiment and theory still remains. We conclude with a what-to-do-list for theorists.

Comments: Invited talk given at the International Conference on Flavor Physics in Zhang-Jia-Jie City, Hunan, China, May 31 - June 6,2001. 6 pages