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

Abstract

Motivated by the recent determination of the top quark mass by the CDF collaboration, $\mt =174 \pm 10 ^{+13}_{-12}$ 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 $\abseps$, the CP-violating parameter in $K$ decays, $\xd = (\delm)/Γ$, the mixing parameter in \bdbdbar\ mixing, the present measurements of the matrix elements $\absvcb$ and $\absvub$, and the $B$-hadron lifetimes. The CDF value for $\mt$ 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 $\xs$, as well as the quantities $\sin 2α$, $\sin 2β$ and $\sin^2γ$, which characterize CP-violating asymmetries in $B$-decays.