A lattice study of the form factors A0 and A3 in the decay B−0 → ϱ+l−ν−l Original Research Article

We report on a lattice calculation of the form factors A0 and A3 for the pseudoscalar to vector meson semileptonic decay B−0 → ϱ+l−ν−l. We find that resonant (or pole-type) contributions alone are unable to describe these two form factors simultaneously. For the quantity A0(q2 = 0), which is important phenomenologically for the determination of |Vub|, we extract a range of values, A0(q2 = 0) = (0.16–0.35)−6+9, where the range is due to systematic uncertainty and the quoted error is statistical. We have also determined A2 (q2 = 0) = 0.28−6−5+9+4.