Implications of the Top Quark Mass Measurements for the CKM Parameters, $\text{xs}$ and CP Asymmetries

Abstract

Motivated by the recent determination of the top quark mass by the CDF collaboration, $\text{mt}=174\pm 10_{-12}^{+13}$ GeV, we review and update constraints on the parameters of the quark flavour mixing matrix $V_{CKM}$ in the standard model. In performing these fits, we use inputs from the measurements of $\text{abseps}$, the CP-violating parameter in $K$ decays, $\text{xd}=(\text{delm})/\Gamma$, the mixing parameter in \bdbdbar\ mixing, the present measurements of the matrix elements $\text{absvcb}$ and $\text{absvub}$, and the $B$-hadron lifetimes. The CDF value for $\text{mt}$ considerably reduces the CKM-parameter space previously allowed. An interesting result of our analysis is that the present data can be used to restrict the coupling constant product ratio $f_{B_d}\sqrt{B_{B_d}}$ to the range 110-270 MeV -- in comfortable agreement with existing theoretical estimates of this quantity. We use the updated CKM matrix to predict the \bsbsbar\ mixing ratio $\text{xs}$, as well as the quantities $\sin 2\alpha$, $\sin 2\beta$ and ${\sin }^2\gamma$, which characterize CP-violating asymmetries in $B$-decays.

Comments: 18 pages and 5 figures (not included, can be obtained by request), LaTeX, CERN Report, CERN-TH.7248/94 (May 1994); UdeM-LPN-TH-94-117. (Corrected version; typos corrected in section 6 in the line following Eq. (34).)