B meson leptonic decay constant with quenched lattice NRQCD ( JLQCD Collaboration )

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(αsa) and O(αs/M) corrections. Using simulations at three value of couplings β=5.7, 5.9 and 6.1 on lattices of size 123×32, 163×48 and 243×64, we find no significant a dependence in fB if the O(αsa) correction is included in the axial current. We obtain fB = 167(7)(15) MeV, fBs = 191(4)(17)( +4 −0) MeV and fBs/fB = 1.15(3)(1)( +3 −0), 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. PACS number(s): 12.38.Gc, 12.39.Hg, 13.20.He, 14.40.Nd Typeset using REVTEX