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 = 1993 MeV for B mesons and fD = 1972 MeV, fDs = 2242 MeV for D mesons where the errors are statistical. In addition we expect a 5% ( 7-1.973389or D mesons) systematic error and a 5 6.880872e-316rror in the uncertainty to determine the lattice scale, besides the quenching error, which is not estimated in this Letter