Abstract :
We test the internal consistencies and the reliability of the existing estimates of the decay constant fB in the static limit, the meson-quark mass gap Λ and the kinetic energy K of a heavy quark obtained from the heavy quark effective theory (HQET)-sum rules. Finite energy local duality sum rules (FESR) have also been used to fix approximatively the value of the continuum energy and to study the correlations among these different parameters. Then, we deduce to two-loop accuracy: Λ = (0.65 ± 0.05) GeV, K = − (0.5 ± 0.2) GeV2, implying the value of the pole mass in HQET: Mb = (4.61 ± 0.05) GeV. By combining the results from the sum rules in HQET and in the full theory, we obtain ƒB∞ = (1.98±0.31)ƒπ and the quark mass dependence of the pseudoscalar decay constant: ƒpMp = (0.33 ± 0.06) GeV32 αs1β1 {1 − 2αs3π − 1.1/MQ + 0.7/MQ2.
