Decay constants of B and D mesons from non-perturbatively improved lattice QCD

The decay constants of B and D mesons are computed in quenched lattice QCD at two dierent values of the coupling. The action and operators areO(a )i mproved with non-perturbative coecients where available. The results are fB = 218 +5 5 +5 41 MeV, fD = 220 +3 3 +2 24 MeV, fBs = 242 +4 4 +13 48 MeV, fDs = 241 +2 2 +7 30 MeV. Systematic errors are discussed in detail. Results for vector decay constants, avour symmetry breaking ratios of decay constants, the pseudoscalar-vector mass splitting and D meson masses are also presented.