Mixing and CP violation in K- and B-mesons: A lattice QCD point of view

We have analyzed K0-anti K0 and B0-anti B0 mixing on the basis of the most recent experimental results and theoretical lattice determination of the relevant matrix elements. We find that a top mass larger than 140 GeV and fB≥200 MeV, as suggested by recent lattice calculations, imply a CP-violating asymmetry in B→J/ψ+Ks decays much larger than previously estimated. We also report the corresponding theoretical prediction for ε'/ε, for which rather large experimental and theoretical uncertainties still exist. (orig.)