Heavy Meson Decay Constants from Quenched Lattice QCD

A quenched lattice QCD calculation of the B and D meson decay constants is presented. To investigate scaling violation associated with the heavy quarks, parallel simulations are carried out employing both Wilson and the O(a)-improved clover quark actions. The discretization errors due to the large b quark mass are estimated with the aid of the nonrelativistic interpretation approach of El-Khadra, Kronfeld, and Mackenzie [Phys. Rev. D 55, 3933 (1997)]. As the best values from our simulations at β = 5.9, 6.1, and 6.3 we obtain fB = 173(4) MeV, fBs = 199(3) MeV for B mesons and fD = 197(2) MeV, fDs = 224(2) MeV for D mesons where the errors are statistical. In addition we expect a 5% ( 7% for D mesons) systematic error and a 5% error in the uncertainty to determine the lattice scale, besides the quenching error, which is not estimated in this Letter