Extraction of|Vub|with reduced dependence on shape functions

Abstract

Using BABAR measurements of the inclusive electron spectrum in B {yields} X{sub u}e{nu} decays and the inclusive photon spectrum in B {yields} X{sub s}{gamma} decays, we extract the magnitude of the CKM matrix element V{sub ub}. The extraction is based on theoretical calculations designed to reduce the theoretical uncertainties by exploiting the assumption that the leading shape functions are the same for all b {yields} q transitions (q is a light quark). The results agree well with the previous analysis, have indeed smaller theoretical errors, but are presently limited by the knowledge of the photon spectrum and the experimental errors on the lepton spectrum.