Decay constants of heavy mesons from QCD sum rules

Understand

We present a 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 [1].

• 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 accuracy of the method of sum rules.
• Gaining this control has become possible due to the application of our novel procedure for extracting hadron observables based on a dual threshold depending on the Borel parameter.
• For charmed mesons, we obtain f_D=206.2\pm 7.3 (OPE)\pm 5.1 (syst) MeV and f_Ds=245.3\pm 15.7 (OPE) \pm 4.5 (syst) MeV.