Lattice study of B→π semileptonic decay using nonrelativistic lattice QCD -: art. no. 014502

We present an exploratory lattice study of B-->pi semileptonic decay form factors using nonrelativistic lattice QCD for a heavy quark with a Wilson light quark on a 16(3)x32 quenched lattice at beta=5.8. The matrix elements are calculated at eight values of the heavy quark mass in the range of 1.5-8 GeV and with three values of light quark mass. The 1/m(B) corrections to the matrix elements are found to be fairly small except for the spatial component proportional to the B-meson momentum. We find that the q(2) dependence of the form factor f(+)(q(2)) near q(max)(2) becomes much stronger for a larger heavy quark mass, which may suggest an increase in the pole contribution. We perform a model independent fit of the form factors and study whether the q(2) dependence is consistent with the pole contribution. Although the soft pion theorem predicts f(0)(q(max)(2))=f(B)/f(pi) in the chiral limit, we observe a significant violation of this relation. [S0556-2821(98)00413-5].