B meson leptonic decay constant with quenched lattice NRQCD - art. no. 074501

We present a lattice NRQCD study of the B meson decay constant in the quenc hed approximation with emphasis given to the scaling behavior. The NRQCD ac tion and the heavy-light axial vector current we use include all terms of o rder 1/M and the perturbative O(alpha(s)a) and O(alpha(s)/M) corrections. U sing simulations at three values of couplings beta = 5.7, 5.9, and 6.1 on l attices of sizes 12(3) x 32, 16(3) x 48, and 24(3) x 64, we find a signific ant a dependence disappears in f(B) if the O(alpha(s)a) correction is inclu ded in the axial vector current. We observe that beta = 5.9- 6.1 is the win dow where systematic errors are expected to be minimum within one-loop impr oved theory. Our final results are f(B) = 170(5)(15) MeV, f(Bs) = 191(4)(17 )(-0 +4) MeV, and f(Bs) / f(B) = 1.12(2)(1)(-0 +3), where the first error i s statistical, the second is systematic, and the third is due to the uncert ainty of the strange quark mass, while quenching errors are not included.