Decay Constants of Beauty Mesons from QCD Sum Rules.

Our recently completed analysis of the decay constants of both pseudoscalar and vector beauty mesons reveals that in the bottom-quark sector two specific features of the sum-rule predictions show up: (i) For the input value of the bottom-quark mass in the MS scheme mb(mb) ≈ 4.18 GeV, the sum-rule result fB ≈ 210-220 MeV for the B meson decay constant is substantially larger than the recent lattice-QCD finding fB ≈ 190 MeV. Requiring QCD sum rules to reproduce the lattice-QCD value of fB yields a significantly larger b-quark mass: mb(mb) = 4.247 GeV. (ii) Whereas QCD sum-rule predictions for the charmed-meson decay constants fD, ..., ... and ... are practically independent of the choice of renormalization scale, in the beauty sector the results for the decay constants-- and especially for the ratio ...--prove to be very sensitive to the specific scale setting. [ABSTRACT FROM AUTHOR]