189 research outputs found

    Measurement of the Bs0J/ψKS0B_s^0\to J/\psi K_S^0 branching fraction

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    The Bs0J/ψKS0B_s^0\to J/\psi K_S^0 branching fraction is measured in a data sample corresponding to 0.41fb1fb^{-1} of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to the penguin contributions affecting the sin2β\beta measurement from B0J/ψKS0B^0\to J/\psi K_S^0 The time-integrated branching fraction is measured to be BF(Bs0J/ψKS0)=(1.83±0.28)×105BF(B_s^0\to J/\psi K_S^0)=(1.83\pm0.28)\times10^{-5}. This is the most precise measurement to date

    First observation of the decay Bˉs0D0K0\bar{B}^0_s \to D^0 K^{*0} and a measurement of the ratio of branching fractions B(Bˉs0D0K0)B(Bˉ0D0ρ0)\frac{{\cal B}(\bar{B}^0_s \to D^0 K^{*0})}{{\cal B}(\bar{B}^0 \to D^0 \rho^0)}

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    The first observation of the decay Bˉs0D0K0\bar{B}^0_s \to D^0 K^{*0} using pppp data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb1^{-1}, is reported. A signal of 34.4±6.834.4 \pm 6.8 events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The Bˉs0D0K0\bar{B}^0_s \to D^0 K^{*0} branching fraction is measured relative to that of Bˉ0D0ρ0\bar{B}^0 \to D^0 \rho^0: B(Bˉs0D0K0)B(Bˉ0D0ρ0)=1.48±0.34±0.15±0.12\frac{{\cal B}(\bar{B}^0_s \to D^0 K^{*0})}{{\cal B}(\bar{B}^0 \to D^0 \rho^0)} = 1.48 \pm 0.34 \pm 0.15 \pm 0.12, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the B0B^0 and Bs0B^0_s hadronisation fractions.Comment: 10 pages, 3 figures, submitted to Phys. Lett. B; ISSN 0370-269

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Etnobotânica e medicina popular no tratamento de malária e males associados na comunidade ribeirinha Julião – baixo Rio Negro (Amazônia Central)

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    RESUMO A utilização de plantas medicinais para o tratamento de doenças tropicais como a malária na Amazônia Central é de suma importância, principalmente em locais onde o sistema único de saúde não se encontra presente como na maioria das comunidades ribeirinhas desta região. Sendo assim, investigar e resgatar o conhecimento popular a respeito de plantas medicinais utilizadas no tratamento de malária e males associados pelos moradores da comunidade Julião situada na Reserva de Desenvolvimento Sustentável do Tupé, Manaus-AM, torna-se importante no registro de como as populações locais se previnem e tratam essa doença tão prevalente e perigosa na região. O trabalho foi conduzido na forma de oficinas participativas, segregadas por gênero e complementadas com entrevistas semiestruturadas aliadas à técnica da turnê-guiada nos quintais e floresta adjacente à comunidade. Foram calculados os índices de diversidade de Shannon-Wiener, equitabilidade e concordância quanto ao uso principal (CUP). A partir da colaboração efetiva de 13 comunitários foram registradas 62 espécies vegetais pertencentes a 53 gêneros e 34 famílias botânicas que resultaram em índice de diversidade (H’) de 1,62 decits e equitabilidade de 0,9. As famílias mais representativas foram: Fabaceae (7 espécies), Asteraceae e Lamiaceae (4 espécies cada) e Solanaceae e Rutaceae (3 espécies cada). Vale destacar que 16 espécies (25,8%) foram citadas para tratamento de malária e males associados pela primeira vez em estudos etnobotânicos realizados na América Latina
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