477 research outputs found

    Answering PICO Clinical Questions: a Semantic Graph-Based Approach

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    International audienceIn this paper, we tackle the issue related to the retrieval of the best evidence that fits with a PICO (Population, Intervention, Comparison and Outcome) question. We propose a new document ranking algorithm that relies on semantic based query expansion bounded by the local search context to better discard irrelevant documents. Experiments using a standard dataset including 423 PICO questions and more than 1,2 million of documents, show that our aproach is promising

    Exotic Meson Production in the f1(1285)π−f_{1}(1285)\pi^{-} System observed in the Reaction π−p→ηπ+π−π−p\pi^{-} p \to \eta\pi^{+}\pi^{-}\pi^{-} p at 18 GeV/c

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    This letter reports results from the partial wave analysis of the π−π−π+η\pi^{-}\pi^{-}\pi^{+}\eta final state in π−p\pi^{-}p collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, JPC=1−+J^{PC} = 1^{-+} in the decay channel f1(1285)π−f_{1}(1285)\pi^{-}. The mass M=1709±24±41M = 1709 \pm 24 \pm 41 MeV/c^2 and width Γ=403±80±115\Gamma = 403 \pm 80 \pm 115 MeV/c^2 of the first state are consistent with the parameters of the previously observed π1(1600)\pi_{1}(1600). The second resonance with mass M=2001±30±92M = 2001 \pm 30 \pm 92 MeV/c^2 and width Γ=333±52±49\Gamma = 333 \pm 52 \pm 49 MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of π2(1900)\pi_{2}(1900) is confirmed with mass M=2003±88±148M = 2003 \pm 88 \pm 148 MeV/c^2 and width Γ=306±132±121\Gamma = 306 \pm 132 \pm 121 MeV/c^2 and a new state, a1(2096)a_{1}(2096), is observed with mass M=2096±17±121M = 2096 \pm 17 \pm 121 MeV/c^2 and width Γ=451±41±81\Gamma = 451 \pm 41 \pm 81 MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers

    CP--violating Chargino Contributions to the Higgs Coupling to Photon Pairs in the Decoupling Regime of Higgs Sector

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    In most supersymmetric theories, charginos χ~1,2±\tilde{\chi}^\pm_{1,2} belong to the class of the lightest supersymmetric particles and the couplings of Higgs bosons to charginos are in general complex so that the CP--violating chargino contributions to the loop--induced coupling of the lightest Higgs boson to photon pairs can be sizable even in the decoupling limit of large pseudoscalar mass mAm_A with only the lightest Higgs boson kinematically accessible at future high energy colliders. We introduce a specific benchmark scenario of CP violation consistent with the electric dipole moment constraints and with a commonly accepted baryogenesis mechanism in the minimal supersymmetric Standard Model. Based on the benchmark scenario of CP violation, we demonstrate that the fusion of the lightest Higgs boson in linearly polarized photon--photon collisions can allow us to confirm the existence of the CP--violating chargino contributions {\it even in the decoupling regime of the Higgs sector} for nearly degenerate SU(2) gaugino and higgsino mass parameters of about the electroweak scale.Comment: 1+13 pages, 3 eps figure

    Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System

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    The exclusive reaction π−p→ηπ0n\pi^- p \to \eta \pi^0 n, η→π+π−π0\eta \to \pi^+ \pi^- \pi^0 at 18 GeV/c/c has been studied with a partial wave analysis on a sample of 23~492 ηπ0n\eta \pi^0 n events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the P+P_+ wave, thus providing evidence for a neutral exotic meson with JPC=1−+J^{PC} = 1^{-+}, a mass of 1257±20±251257 \pm 20 \pm 25 MeV/c2/c^2, and a width of 354±64±60354 \pm 64 \pm 60 MeV/c2/c^2. New interpretations of the meson exotics in neutral ηπ0\eta \pi^0 system observed in E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase variations. p4, rewording paragrath "The second method ..." . p4, at the bottom of paragrath "The third method ..." added consistent with the results of methods 1 and 2

    Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c

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    Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures and 1 tabl

    Observation of Pseudoscalar and Axial Vector Resonances in pi- p -> K+ K- pi0 n at 18 GeV

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    A new measurement of the reaction pi- p -> K+ K- pi0 n has been made at a beam energy of 18 GeV. A partial wave analysis of the K+ K- pi0 system shows evidence for three pseudoscalar resonances, eta(1295), eta(1416), and eta(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed masses, widths and decay properties are reported. No signal was observed for C(1480), an IG J{PC} = 1+ 1{--} state previously reported in phi pi0 decay.Comment: 7 pages, 6 figs, to be submitted to Phys. Let

    Search for Exotic Mesons in pi- P Interactions at 18 GeV/c

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    The recent search for non qqˉq \bar{q} mesons in π−p\pi^{-}p interactions at Brookhaven National Laboratory is summarized. Many final states such as ηπ\eta \pi, ηâ€Čπ−\eta' \pi^{-}, a0πa_{0} \pi, f1πf_{1} \pi, a2πa_{2} \pi, b1πb_{1} \pi, which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear Physics, Erice, Sicily, Italy, September 199

    MSSM Higgs sector CP violation at photon colliders: Revisited

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    We present a comprehensive analysis on the MSSM Higgs sector CP violation at photon colliders including the chargino contributions as well as the contributions of other charged particles. The chargino loop contributions can be important for the would-be CP odd Higgs production at photon colliders. Polarization asymmetries are indispensable in determining the CP properties of neutral Higgs bosons.Comment: 24 pages, 40 figure

    Evidence for a narrow dip structure at 1.9 GeV/c2^2 in 3π+3π−3\pi^+ 3\pi^- diffractive photoproduction

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    A narrow dip structure has been observed at 1.9 GeV/c2^2 in a study of diffractive photoproduction of the  3π+3π−~3\pi^+3\pi^- final state performed by the Fermilab experiment E687.Comment: The data of Figure 6 can be obtained by downloading the raw data file e687_6pi.txt. v5 (2nov2018): added Fig. 7, the 6 pion energy distribution as requested by a reade

    Study of Hadronic Five-Body Decays of Charmed Mesons

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    We study the decay of D+ and Ds+ mesons into charged five body final states, and report the discovery of the decay mode D+ -> K+K-Pi+Pi+Pi-, as well as measurements of the decay modes D+ -> K-Pi+Pi+Pi+Pi-, Ds+ -> K+K-Pi+Pi+Pi-, Ds+ -> PhiPi+Pi+Pi- and D+/Ds+ -> Pi+Pi+Pi+Pi-Pi-. An analysis of the resonant substructure is also included, with evidence suggesting that both decays proceed primarily through an a1 vector resonance.Comment: 11 pages, 3 figure
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