1,645 research outputs found

    Complete Next to Leading Order QCD Corrections to the Photon Structure Functions F2γ(x,Q2)F^\gamma_2(x,Q^2) and FLγ(x,Q2)F_L^\gamma(x,Q^2)

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    We present the complete NLO QCD analysis of the photon structure functions F2γ(x,Q2)F_2^\gamma(x,Q^2) and FLγ(x,Q2)F_L^\gamma(x,Q^2) for a real photon target. In particular we study the heavy flavor content of the structure functions which is due to two different production mechanisms, namely collisions of a virtual photon with a real photon, and with a parton. We observe that the charm contributions are noticeable for F2γ(x,Q2)F_2^\gamma(x,Q^2) as well as FLγ(x,Q2)F_L^\gamma(x,Q^2) in the x-region studied.Comment: Latex 34 pages, 24 figures, uuencoded, attached at end, ITP-SB-93-46, FERMILAB-Pub-93/240-T, SMU HEP 93-1

    Search for CP violation in tau -> K^0_S pi nu_tau decays at Belle

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    We report on a search for CP violation in tau -> K^0_S pi nu_tau decays using a data sample of 699 fb^{-1} collected in the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K^0_S pi system and found to be compatible with zero with a precision of O(10^{-3}) in each mass bin. Limits for the CP violation parameter Im(eta_S) are given at a 90 % confidence level. These limits are |Im(eta_S)|<0.026 or better, depending on the parameterization used to describe the hadronic form factors and improve upon previous limits by one order of magnitude

    Observation of B+ -> Dbar*0 tau+ nu_tau and Evidence for B+ -> Dbar^0 tau+ nu_tau at Belle

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    We present measurements of B+ -> Dbar*0 tau+ nu_tau and B+ -> Dbar^0 tau+ nu_tau decays in a data sample of 657 x 10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find 446^{+58}_{-56} events of the decay B+ -> Dbar*0 tau+ nu_tau with a significance of 8.1 standard deviations, and 146^{+42}_{-41} events of the decay B+ -> Dbar0 tau+ nu_tau with a significance of 3.5 standard deviations. The latter signal provides the first evidence for this decay mode. The measured branching fractions are B(B+ -> Dbar*0 tau+ nu_tau)=(2.12^{+0.28}_{-0.27} (stat) +- 0.29 (syst)) % and B(B+ -> Dbar0 tau+ nu_tau)=(0.77 +- 0.22 (stat) +- 0.12 (syst)) %.Comment: 6 pages, 4 figures, submitted to Phys. Rev. Let

    Evidence for a new resonance and search for the Y(4140) in γγϕJ/ψ\gamma \gamma \to \phi J/\psi

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    The process \gamma \gamma \to \phi \jpsi is measured for \phi \jpsi masses between threshold and 5 GeV/c2{\it c}^2, using a data sample of 825 fb1^{-1} collected with the Belle detector. A narrow peak of 8.83.2+4.28.8^{+4.2}_{-3.2} events, with a significance of 3.2 standard deviations including systematic uncertainty, is observed. The mass and natural width of the structure (named X(4350)) are measured to be (4350.65.1+4.6(stat)±0.7(syst))MeV/c2(4350.6^{+4.6}_{-5.1}(\rm{stat})\pm 0.7(\rm{syst})) \hbox{MeV}/{\it c}^2 and (139+18(stat)±4(syst))MeV(13^{+18}_{-9}(\rm{stat})\pm 4(\rm{syst})) \hbox{MeV}, respectively. The product of its two-photon decay width and branching fraction to \phi\jpsi is (6.72.4+3.2(stat)±1.1(syst))eV(6.7^{+3.2}_{-2.4}(\rm{stat}) \pm 1.1(\rm{syst})) \hbox{eV} for JP=0+J^P=0^+, or (1.50.6+0.7(stat)±0.3(syst))eV(1.5^{+0.7}_{-0.6}(\rm{stat}) \pm 0.3(\rm{syst})) \hbox{eV} for JP=2+J^P=2^+. No signal for the Y(4140)\to \phi \jpsi structure reported by the CDF Collaboration in B\to K^+ \phi \jpsi decays is observed, and limits of \Gamma_{\gamma \gamma}(Y(4140)) \BR(Y(4140)\to\phi \jpsi)<41 \hbox{eV} for JP=0+J^P=0^+ or <6.0eV<6.0 \hbox{eV} for JP=2+J^P=2^+ are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a Ds+DsD_{s}^{\ast+} {D}_{s}^{\ast-} molecule.Comment: 9 pages, 3 figures, publication in Phys. Rev. Lett. 104, 112004, 201

    Evidence for direct CP violation in the decay B->D(*)K, D->KsPi+Pi- and measurement of the CKM phase phi3

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    We present a new measurement of the unitarity triangle angle phi3 using a Dalitz plot analysis of the KsPi+Pi- decay of the neutral D meson produced in B->D(*)K decays. The method exploits the interference between D0 and D0bar to extract the angle phi3, strong phase delta and the ratio r of suppressed and allowed amplitudes. We apply this method to a 605 fb-1 data sample collected by the Belle experiment. The analysis uses three decays: B->DK, and B->D*K with D*->DPi0 and D*->Dgamma, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain phi3 = 78.4^+10.8_-11.6 +- 3.6 (syst) +- 8.9 (model) degrees. CP conservation in this process is ruled out at the confidence level (1-CL)=5x10^-4, or 3.5 standard deviations.Comment: 10 pages, 5 figures, 4 tables. Replaced by version published in Phys. Rev.

    First Measurement of Inclusive B -> X_s eta Decays

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    We report a first measurement of inclusive B -> X_s eta decays, where X_s is a charmless state with unit strangeness. The measurement is based on a pseudo-inclusive reconstruction technique and uses a sample of 657 x 10^6 BB-bar pairs accumulated with the Belle detector at the KEKB e^+e^- collider. For M_{X_s} < 2.6 GeV/c^2, we measure a branching fraction of (26.1 +/- 3.0 (stat) +1.9 -2.1 (syst) +4.0 -7.1 (model)) x 10^-5 and a direct CP asymmetry of A_{CP} = -0.13 +/- 0.04 +0.02 -0.03. Over half of the signal occurs in the range M_{X_s} > 1.8 GeV/c^2.Comment: 6 pages, 1 figure, 1 table, submitted to Physical Review Letter

    The main concerns of European anaesthesiology postgraduate trainees: A European survey

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    This is the first study intended to identify the European anaesthesiology trainees' main concerns, to initiate a process of improvement of the training in anaesthesiology by the European Society of Anaesthesiology (ESA). The authors developed an electronic survey which addressed seven different concerns: autonomy transition, technical skills, exchange programs, residency costs, residency workload, employment prospects and educational contents/preparation for the European Diploma in Anaesthesiology and Intensive Care (EDAIC). The survey was disseminated by email to all anaesthesiology trainees registered in ESA and all European National Societies were asked to distribute the survey to their graduating trainees. 665 trainees initiated the survey with a completion rate of 54.6%. The trainees' main concerns were in descending order: educational contents, residency costs, employment prospects, residency workload, exchange programs, technical skills and autonomy transition. This report analyzes the three main concerns in more detail. 68% of respondents were unaware of the existence of the ESA e-learning platform. Other means to improve the preparation for the EDAIC such as a multiple-choice questions book should be developed. The main reason for not becoming an ESA Trainee member was the associated cost and 68% of respondents gave up activities or opportunities during their residency due to economic constraints; 56% of respondents considered emigrating for economic reasons and 28% elected Northern/Central Europe. The results of the present survey may provide additional background information for the development of specific improvements in strategies for training in anaesthesiology. (c) 2018 Elsevier Ltd. All rights reserved

    Measurement of D+KS0K+D^+ \to K_S^0 K^+ and Ds+KS0π+D^+_s \to K_S^0 \pi^+ branching ratios

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    We report an improved measurement of D+KS0K+D^+ \to K_S^0 K^+ and Ds+KS0π+D^+_s\to K_S^0 \pi^+ branching ratios using 605 fb1^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e+ee^+ e^- collider. The measured branching ratios with respect to the Cabibbo-favored modes are B(D+KS0K+)/B(D+KS0π+)\mathcal{B}(D^+ \to K_S^0 K^+)/\mathcal{B}(D^+ \to K_S^0 \pi^+) = 0.1899±0.0011±\pm0.0011\pm0.0022 and B(Ds+KS0π+)/B(Ds+KS0K+)\mathcal{B}(D^+_s \to K_S^0 \pi^+)/\mathcal{B}(D^+_s \to K_S^0 K^+) = 0.0803±0.0024±\pm0.0024\pm0.0019 where the first uncertainties are statistical and the second are systematic
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