The Unitarity Triangle Fit in the Standard Model and Hadronic Parameters from Lattice QCD: A Reappraisal after the Measurements of Delta mₛ and BR(B to tau nu)

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The recent measurements of the Bₛ meson mixing amplitude by CDF and of the leptonic branching fraction BR(B to tau nu) by Belle call for an upgraded analysis of the Unitarity Triangle in the Standard Model. Besides improving the previous constraints on the parameters of the CKM matrix, these new measurements, combined with the recent determinations of the angles alpha, beta and gamma from non-leptonic decays, allow, in the Standard Model, a quite accurate extraction of the values of the hadronic matrix elements relevant for K-Kbar and Bₛ,d-Bₛ,dbar mixing and of the leptonic decay constant fB. These values, obtained ``experimentally'', can then be compared with the theoretical predictions, mainly from lattice QCD. In this paper we upgrade the UT fit, we determine from the data the kaon B-parameter Bₖhat, the B⁰ mixing amplitude parameters fBs B¹/²Bs and xi, the decay constant fB, and make a comparison of the obtained values with lattice predictions. We also discuss the different determinations of Vᵤb and show that current data do not favour the value measured in inclusive decays.