Radiative corrections to the decay B→πeν and the heavy quark limit

We calculate radiative corrections to the light-cone sum rule for the semileptonic form factor in B --> pi ev decays and thus remove the major uncertainty in determining the CKM mixing angle \V-ub\ by this method. We discuss the remaining uncertainties and perspectives for further studies. The structure of the radiative corrections suggests factorization of soft (end-point) and hard rescattering contributions in heavy-to-light decays in the heavy quark limit. (C) 1998 Elsevier Science B.V.