Lifetime Difference of Neutral $B_s$ Mesons and its Implications

Abstract

We discuss the calculation of the width difference $\Delta {\Gamma }_{B_s}$ between the $B_s$ mass eigenstates to next-to-leading order in the heavy quark expansion. $1/m_b$-corrections are estimated to reduce the leading order result by typically $30\%$. The error of the present estimate $(\Delta \Gamma /\Gamma {)}_{B_s}=0.16_{-0.09}^{+0.11}$ could be substantially improved by pinning down the value of $⟨{\bar{B}}_s|({\bar{b}}_i{s}_i{)}_{S-P}({\bar{b}}_j{s}_j{)}_{S-P}|B_s⟩$ and an accuracy of $10\%$ in $(\Delta \Gamma /\Gamma {)}_{B_s}$ should eventually be reached. We briefly mention strategies to measure $(\Delta \Gamma /\Gamma {)}_{B_s}$, and its implications for constraints on $\Delta M_{B_s}$, CKM parameters and the observation of CP violation in untagged $B_s$ samples.

Comments: 8 pages, LaTeX, sprocl.sty provided (To appear in the Proceedings of the 28th International Conference on High Energy Physics, Warsaw, Poland, 25-31 July 1996)