Browsing by Author "Prencipe, E."
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Item Cross Sections for the Reactions e⁺e⁻ → K⁺ K⁻ π⁺π⁻, K⁺ K⁻ π⁰π⁰, and K⁺ K⁻K⁺ K⁻ Measured Using Initial-State Radiation Events(Amer Physical Soc, 2012-07-26) Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 56366505900 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We study the processes e⁺e⁻ → K⁺ K⁻ π⁺π⁻γ, K⁺ K⁻ π⁰π⁰γ, and K⁺ K⁻ K⁺ K⁻ γ, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb⁻¹ of BABAR data. The invariant mass of the hadronic final state defines the e⁺e⁻ center-of-mass energy, so that the K⁺ K⁻ π⁺π⁻γ data can be compared with direct measurements of the e⁺e⁻ → K⁺ K⁻ π⁺π⁻ reaction. No direct measurements exist for the e⁺e⁻→ K ⁺K ⁻ π⁰π⁰ or e⁺e⁻ → K⁺ K⁻K⁺ K⁻ - reactions, and we present an update of our previous result based on a data sample that is twice as large. Studying the structure of these events, we find contributions from a number of intermediate states and extract their cross sections. In particular, we perform a more detailed study of the e⁺e⁻ → φ(1020)ππγ reaction and confirm the presence of the Y(2175) resonance in the φ(1020)f⁰(980) and K⁺ K⁻ f⁰ (980) modes. In the charmonium region, we observe the J/ψ in all three final states and in several intermediate states, as well as the ψ(2S) in some modes, and measure the corresponding products of branching fraction and electron width.Item Observation and Study of the Baryonic B-Meson Decays B→D^{(*)}pp̅ (π)(π)(American Physical Society, 2012-05-30) Del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present results for B-meson decay modes involving a charm meson, protons, and pions using 455×10⁶ BB̄ pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy e⁺e⁻ collider. The branching fractions are measured for the following ten decays: B̅⁰→D⁰pp̄, B̅⁰→D*⁰pp̄, B̅⁰→D⁺pp̄π⁻, B̅⁰→D*⁺pp̄π⁻, B⁻→D⁰pp̄π⁻, B⁻→D*⁰ pp̄π⁻, B̅⁰→D⁰pp̄→D0pp̄π⁻π⁺, B̅⁰→D*⁰pp̄π⁻π⁺, B⁻→D*⁺pp̅π⁻, B⁻→D⁰pp̄π⁻, B⁻→D*⁰pp̄π⁻, B̅⁰→D⁰pp̄π⁻π⁺, B̅⁰→D*⁰pp̄π⁻π⁺, B⁻→D⁺pp̄π⁻π⁻, and B⁻→D*⁺pp̄π⁻π⁻. The four B⁻ and the two five-body B̅⁰ modes are observed for the first time. The four-body modes are enhanced compared to the three- and the five-body modes. In the three-body modes, the M(pp̄) and M(D^{(*)⁰}p) invariant-mass distributions show enhancements near threshold values. In the four-body mode B̅⁰→D⁺pp̄π⁻, the M(pπ⁻) distribution shows a narrow structure of unknown origin near 1.5 GeV/c². The distributions for the five-body modes, in contrast to the others, are similar to the expectations from uniform phase-space predictions.Item Search for the Decay D⁰ → γγ and Measurement of the Branching Fraction for D⁰ → π⁰π⁰(American Physical Society, 2012-05-18) Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We search for the rare decay of the D⁰ meson to two photons, D⁰ → γγ, and present a measurement of the branching fraction for a D⁰ meson decaying to two neutral pions, B(D⁰ → π⁰π⁰). The data sample analyzed corresponds to an integrated luminosity of 470.5 fb⁻¹ collected by the BABAR detector at the PEP-II asymmetric-energy e⁺e⁻ collider at SLAC. We place an upper limit on the branching fraction, B(D⁰ → γγ) < 2.2 × 10⁻⁶ at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find B(D⁰→π⁰π⁰) = (8.4 ± 0.1 ± 0.4 ± 0.3) × 10⁻⁴.