Decay constant of $B_s$ and $B^*_s$ mesons from ${\rm N_f}=2$ lattice QCD}

Abstract

We report on a two-flavor lattice QCD estimate of the Bs and B * s leptonic decays parameterized by the decay constants fB s and fB * s . In addition to their relevance for phenomenology, their extraction has allowed us to investigate whether the "step scaling in mass" strategy is suitable with Wlilson-Clover fermions to smoothly extrapolate quantities of the heavy-strange sector up to the bottom scale. From the central value of fD s quoted by FLAG at N f = 2 and our ratio f Bs f Ds , we obtain fB s = 212(10)(2)( +2 −10 ) MeV and fB * s /fB s = 1.05(2)( +0 −1 ).