STUDY OF INCLUSIVE AND EXCLUSIVE B → X_u lv DECAYS AND MEASUREMENT OF V_(ub) WITH THE BABAR DETECTOR

摘要

We report studies of B → X_u lv decays, based on a sample of 88 million BB events recorded with the BABAR detector. From both tagged and untagged BB events we have isolated inclusive charmless decays in kinematic regions for which the dominant background from B → X_c lv is reduced by making requirements on different variables: the electron energy E_l, the momentum transfer q~2, and the hadronic mass m_X .Using theoretical calculations we extrapolate to the total decay rate to determine the CKM matrix element |V_(ub)|. In addition, we have measured the branching fraction for exclusive semileptonic decays, such as B → π(ρ, ω, η, a_0)lv. A high signal purity is achieved by selecting events in which a decay of the second B meson is either fully or partially reconstructed.