Improved B→πlνl form factors from the lattice

Abstract We present the results of a lattice computation of the form factors for B 0 → π − l + ν l decays near zero-recoil. These results will allow a determination of the CKM matrix element | V ub | when measurements of the differential decay rate become available. We also provide models for extrapolation of the form factors and rate to the full recoil range. Our computation is performed in the quenched approximation to QCD on a 24 3 ×48 lattice at β =6.2, using a non-perturbatively O (a) -improved action. The masses of all light valence quarks involved are extrapolated to their physical values.