Implications of the Top Quark Mass Measurement for the CKM Parameters, xs and CP Asymmetries (Revised and Updated)

Motivated by the recent determination of the top quark mass by the CDF collaboration, mt = 174 ± 10 −12 GeV, we review and update the constraints on the parameters of the quark flavour mixing matrix VCKM in the standard model. In performing our fits, we use inputs from the measurements of the following quantities: (i) |ǫ|, the CP-violating parameter in K decays, (ii) ∆Md, the mass difference due to the B 0 d-B 0 d mixing, (iii) the matrix elements |Vcb| and |Vub|, and (iv) B-hadron lifetimes. We find that the allowed region of the unitarity triangle is very large, mostly due to theoretical uncertainties. (This emphasizes the importance of measurements of CP-violating rate asymmetries in the B system.) Nevertheless, the present data do somewhat restrict the allowed values of the coupling constant product fBd √ B̂Bd and the renormalization-scale-invariant bag constant B̂K . With the updated CKM matrix we present the currently-allowed range of the ratio |Vtd/Vts|, as well as the standard model predictions for the B s -B s mixing parameter xs and the quantities sin 2α, sin 2β and sin γ, which characterize the CP-asymmetries in B-decays. The ALEPH collaboration has recently reported a significant improvement on the lower limit on the B s -B 0 s mass difference, ∆Ms/∆Md > 11.3 (95% C.L.). This has interesting consequences for the CKM parameters which are also worked out. Submitted to Zeitschrift für Physik C CERN-TH.7398/94 August 1994 ∗On leave of absence from DESY, Hamburg, FRG.