Deborah Bard (SLAC)
We use the Upsilon(4S) dataset collected with the Babar detector at the PEP-II asymmetric e+e- storage ring to study the penguin decay modes. Here we report on a study of the radiative penguin decay B -> Xs gamma at BABAR using lepton-tagging to identify BBbar events. We present new results on the B -> Xs gamma branching fraction and direct CP asymmetry, based on a sample of 380 million BBbar pairs. We also present new results of a search for B -> X_d gamma decays. We consider seven final states with up to four charged pions and one neutral pion or \eta, which correspond to about 50% of the total X_d fragmentation in the mass range investigated. We observe for the first time a significant b->d gamma transition in the hadronic mass range M(Xd) > 1 GeV, resulting in a significant improvement in the determination of |Vtd/Vts| via the ratio of inclusive widths.
Collaboration BABAR (SLAC)