B meson leptonic decay constant with quenched lattice NRQCD

We present a lattice NRQCD study of the B meson decay constant in the quenched approximation with emphasis given to the scaling behavior. The NRQCD action and the heavy-light axial current we use include all terms of order 1/M and the perturbative O(�sa) and O(�s/M) corrections. Using simulations at three value of couplings �=5.7, 5.9 and 6.1 on lattices of size 12 3 ×32,16 3 ×48 and 24 3 ×64, we find no significant a dependence in fB if the O(�sa) correction is included in the axial current. We obtain fB = 167(7)(15) MeV, fBs = 191(4)(17)( +40 ) MeV and fBs /fB = 1.15(3)(1)( +30 ), with the first error being statistical, the second systematic, and the third due to uncertainty of strange quark mass, while quenching errors being not included.