A LATTICE STUDY OF THE FORM-FACTORS A(0) AND A(3) IN THE DECAY (B)OVER-BAR(0)-]RHO(-)(NU)OVER-BAR(L)()L()

We report on a lattice calculation of the form factors A(0) and A(3) f or the pseudoscalar to vector meson semileptonic decay (B) over bar(0) --> rho(+)l(-)<(nu)over bar>(1). We find that resonant (or pole-type) contributions alone are unable to describe these two form factors sim ultaneously. For the quantity A(0)(q(2) = 0), which is important pheno menologically for the determination of \V-ub\, we extract a range of v alues, A(0)(q(2) = 0) = (0.16-0.35)(-6)(+9), where the range is due to systematic uncertainty and the quoted error is statistical. We have a lso determined A(2)(q(2) = 0) = 0.28(-6-5)(+9+4).