Neutral B Meson Mixing and Decay Constants from Lattice QCD

We present updates of our results for neutral $B$-meson mixing and leptonic decay constants obtained in the quenched approximation from a mean-field-improved Sheikholeslami-Wohlert action at two values of lattice spacing. We consider quantities such as $B_{B_{d(s)}}$, $f_{D_{(s)}}$, $f_{B_{(s)}}$ and the full $\mathrm{\Delta }B=2$ matrix-elements, as well as the corresponding SU(3)-breaking ratios.