Decay constants of heavy pseudoscalar mesons from QCD sum rules

Wolfgang Lucha (1) , Dmitri Melikhov (1, 2, 3) , Silvano Simula (4)

1 HEPHY
2 SINP
3 Faculty of Physics [Vienna]
4 Sezione di Roma III

We revisit the sum-rule extraction of the decay constants of the D, Ds, B, and Bs mesons from the two-point correlator of heavy-light pseudoscalar currents. We use the operator product expansion of this correlator expressed in terms of the MS heavy-quark mass, for which the perturbative expansion exhibits a reasonable convergence. Our main emphasis is laid on the control over the uncertainties in the decay constants, related both to the input QCD parameters and to the limited intrinsic accuracy of the method of QCD sum-rules. This becomes possible due to the application of our procedure of extracting hadron observables that involves as novel feature dual thresholds depending on the Borel parameter. For charmed mesons, we find the decay constants fD = (206.2±7.3 (OPE) ±5.1 (syst)) MeV and fD s = (245.3±15.7 (OPE) ±4.5 (syst)) MeV. For beauty mesons, the decay constants turn out to be extremely sensitive to the precise value of m b (m b). By requiring our sum-rule estimate to match the average of the lattice results for fB, a very accurate value m b (m b) = 4.245 ± 0.025 GeV is extracted, leading to fB = (193.4 ± 12.3 (OPE) ± 4.3 (syst)) MeV and fB s = (232.5 ± 18.6 (OPE) ± 2.4 (syst)) MeV.

Mots clés: 11.55.Hx; 12.38.Lg; 03.65.Ge

Wolfgang Lucha, Dmitri Melikhov, Silvano Simula. Decay constants of heavy pseudoscalar mesons from QCD sum rules. Journal of Physics G: Nuclear and Particle Physics, 2011, 38 (10), pp.105002. ⟨10.1088/0954-3899/38/10/105002⟩. ⟨hal-00655647⟩