The unitarity triangle fit in the standard model and hadronic parameters from lattice QCD: A reappraisal after the measurements of Δms and BR(B → τντ)

Abstract

The recent measurements of the B0s meson mixing amplitude by CDF and of the leptonic branching fraction BR(B → τντ) 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 α, β and γ from non-leptonic decays, allow, in the Standard Model, a quite accurate extraction of the values of the hadronic matrix elements relevant for K 0-K̄0 and Bs,d0-B̄ s,d0 mixing and of the leptonic decay constant f B. In this paper we upgrade the UT fit, we determine from the data the kaon B-parameter B̂K, the B0 mixing amplitude parameters fBsB̂Bs1/2 and ξ, the decay constant fB, and make a comparison of the obtained values with lattice predictions. We also discuss the different determinations of V ub and show that current data do not favour the value measured in inclusive decays. © SISSA 2006.