We investigate the scaling behavior of the B meson decay constant fB and
fBs at β=5.7,5.9,6.1, employing the NRQCD heavy quark
action and the clover light quark action. Mixing effect from dimension-4
operator in the heavy-light axial-vector current is studied, and we find that
the a dependence of fB is significantly reduced. Our preliminary result
for the decay constants in the quenched approximation is
fB=162(−18+35) MeV, fBs=190(−19+40) MeV, and
fBs/fB=1.18(−6+6).Comment: LATTICE98(matrixelement), 3 pages, 3 eps figure