HEAVY MESON DECAY CONSTANTS FROM QUENCHED LATTICE QCD

A quenched lattice QCD calculation of the B and D meson decay constant s is presented. To investigate scaling violation associated with the h eavy quarks, parallel simulations are carried out employing both Wilso n and the O(a)-improved clover quark actions. The discretization error s due to the large b quark mass are estimated with the aid of the nonr elativistic interpretation approach of El-Khadra, Kronfeld, and Macken zie [Phys. Rev. D 55, 3933 (1997)]. As the best values from our simula tions at beta = 5.9, 6.1, and 6.3 we obtain f(B) = 173(4) MeV, f(Bs) = 199(3) MeV for B meson and f(D) = 197(2) MeV, f(Ds) = 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 t o determine the lattice scale, besides the quenching error, which is n ot estimated in this Letter.