Lattice study of the decay B0→ρ+ l- anti νl: model-independent determination of vertical stroke Vub vertical stroke

We present results of a lattice computation of the vector and axial-vector current matrix elements relevant for the semileptonic decay B0→ρ+ l-anti νl. The computations are performed in the quenched approximation of lattice QCD on a 243 x 48 lattice at β= 6.2, using an O (a) improved fermionic action. Our principal result is for the differential decay rate, dΓ/dq2, for the decay B0→ρ+ l- anti νl in a region beyond the charm endpoint, allowing a model-independent extraction of vertical stroke Vub vertical stroke from experimental measurements. Heavy quark symmetry relations between radiative and semileptonic decays of B mesons into light vector mesons are also discussed. (orig.)