Measurements of the B -> Xs gamma Branching Fraction and Photon Spectrum from a Sum of Exclusive Final States
Abstract
Using 88.9 million BB events collected by the BaBar detector at the Y(4S), we measure the branching fraction for the radiative penguin process B -> Xs gamma from the sum of 38 exclusive final states. The inclusive branching fraction above a minimum photon energy Egamma > 1.9 GeV is BF (b -> s gamma) = (3.27 +/- 0.18 (stat.) +0.55/-0.40 (syst.) +0.04/-0.09 (theory)) 10-4. We also measure the isospin asymmetry between B- -> Xs ubar gamma and B0bar -> Xs dbar gamma to be Delta0- = -0.006 +/- 0.058 (stat.) +/- 0.009 (syst.) +/- 0.024 (B0bar / B-). The photon energy spectrum is measured in the B rest frame, from which moments are derived for different values of the minimum photon energy. We present fits to the photon spectrum and moments which give the heavy-quark parameters mb and mupi2. The fitted parameters are consistent with those obtained from semileptonic B -> Xc l nu decays, and are useful inputs for the extraction of Vub from measurements of semileptonic B -> Xu l nu decays.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.