Determination of Vub from B->pi l nu on the lattice

We present results of a lattice study of the form factors in the decay B-> pi l nu. We attempt to disentangle the the dependence of the form factors on the light quark masses and the momentum transfer. Using models of the q^2 dependence we calculate the total decay rate, and compare to the experimental measure to extract Vub. This study was performed in the quenched approximation at beta=6.2 on a 24^3 X 48 lattice, with a non-perturbatively improved SW fermion action.