B-0-(B)over-bar(0) mixing and decay constants with the non-perturbatively improved action

Several quantities relevant to phenomenological studies of B-0-(B) over bar (0) mixing are computed on the lattice. Our main results are f(Bd) root(B) over cap (Bd) = 206(28) (14)(-00)(+31) MeV, xi = f(Bd) root(B) over capB(x)/f(Bd) root(B) over cap (Bd) = 1.16(7). We also obtain the related quantities f(Bs) root(B) over cap (Bs) - 237(18) (10)(-00)(+34) MeV, f(Bd) = 174(22)(-0-0-00)(+7+5+26) MeV, f(Bs) = 204(15)(-0-0-00)(+7+4+31) MeV, f(Bs)/f(Bd) = 1.17(4)(-1)(+0), f(Bd)/f(Ds) = 0.74(5). After combining our results with the experimental world average Deltam(d)((exp)), we predict Deltam(s) = 15.8(2.1)(3.3) ps(-1). We have also computed the relevant parameters for D-0-(D) over bar (0) mixing…