B and Bs decay constants from moments of finite energy sum rules in QCD

Abstract.We use an appropriate combination of moments of finite energy sum rules in QCD in order to compute the Bq-meson decay constants fB and $f_{B_s}$. We perform the calculation using a two-loop computation of the imaginary part of the pseudoscalar two point function in terms of the running bottom quark mass. The results are stable against the so-called QCD duality threshold, and they are in agreement with the estimates obtained from Borel transform QCD sum rules and lattice computations.