Implications of the top quark mass measurement for the CKM parameters,xs and CP asymmetries

AbstractMotivated by the recent determination of the top quark mass by the CDF collaboration,mt=174±10−12+13 GeV, we review and update the constraints on the parameters of the quark flavour mixing matrixVCKM in the standard model. In performing our fits, we use inputs from the measurements of the following quantities: (i) |∈|, the CP-violating parameter inK decays, (ii) ΔMd, the mass difference due to the $$B_d^0 - \overline {B_d^0 }$$ 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 theB system.) Nevertheless, the present data do some-what restrict the allowed values of the coupling constant product $$f_{B_d } \sqrt {\hat B_{B_d } }$$ and the renormalization-scale-invariant bag constant $$\hat B_K$$ . 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 $$B_s^0 - \overline {B_s^0 }$$ mixing parameterxs and the quantities sin 2α, sin 2β and sin2 γ, which characterize the CP-asymmetries inB-decays. The ALEPH collaboration has recently reported a significant improvement on the lower limit on the $$B_s^0 - \overline {B_s^0 }$$ mass difference, ΔMs/Δxd>11.3 (95% C.L.). This has interesting consequences for the CKM parameters which are also worked out.