823 research outputs found

    Averages of bb-hadron, cc-hadron, and τ\tau-lepton properties as of summer 2014

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    This article reports world averages of measurements of bb-hadron, cc-hadron, and τ\tau-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through summer 2014. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CPCP violation parameters, parameters of semileptonic decays and CKM matrix elements.Comment: 436 pages, many figures and tables. Online updates available at http://www.slac.stanford.edu/xorg/hfag

    Antimicrobial use in European acute care hospitals: results from the second point prevalence survey (PPS) of healthcare-associated infections and antimicrobial use, 2016 to 2017

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    Antimicrobial agents used to treat infections are life-saving. Overuse may result in more frequent adverse effects and emergence of multidrug-resistant microorganisms. In 2016-17, we performed the second point-prevalence survey (PPS) of healthcare-associated infections (HAIs) and antimicrobial use in European acute care hospitals. We included 1,209 hospitals and 310,755 patients in 28 of 31 European Union/European Economic Area (EU/EEA) countries. The weighted prevalence of antimicrobial use in the EU/EEA was 30.5% (95% CI: 29.2-31.9%). The most common indication for prescribing antimicrobials was treatment of a community-acquired infection, followed by treatment of HAI and surgical prophylaxis. Over half (54.2%) of antimicrobials for surgical prophylaxis were prescribed for more than 1 day. The most common infections treated by antimicrobials were respiratory tract infections and the most commonly prescribed antimicrobial agents were penicillins with beta-lactamase inhibitors. There was wide variation of patients on antimicrobials, in the selection of antimicrobial agents and in antimicrobial stewardship resources and activities across the participating countries. The results of the PPS provide detailed information on antimicrobial use in European acute care hospitals, enable comparisons between countries and hospitals, and highlight key areas for national and European action that will support efforts towards prudent use of antimicrobials

    Search for double charmonium decays of the P-wave spin-triplet bottomonium states

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    Using a sample of 158 million ΄(2S)\Upsilon(2S) events collected with the Belle detector, we search for the first time for double charmonium decays of the PP-wave spin-triplet bottomonium states (΄(2S)â†’ÎłÏ‡bJ\Upsilon(2S) \to \gamma \chi_{bJ}, \chi_{bJ} \to \jpsi \jpsi, \jpsi \psp, \psp \psp for J=0, 1, and 2). No significant χbJ\chi_{bJ} signal is observed in the double charmonium mass spectra, and we obtain the following upper limits, \BR(\chi_{bJ} \to \jpsi \jpsi)<7.1\times 10^{-5}, 2.7×10−52.7\times 10^{-5}, 4.5×10−54.5\times 10^{-5}, \BR(\chi_{bJ} \to \jpsi \psp)<1.2\times 10^{-4}, 1.7×10−51.7\times 10^{-5}, 4.9×10−54.9\times 10^{-5}, \BR(\chi_{bJ} \to \psp \psp)<3.1\times 10^{-5}, 6.2×10−56.2\times 10^{-5}, 1.6×10−51.6\times 10^{-5} for J=0, 1, and 2, respectively, at the 90% confidence level. These limits are significantly lower than the central values (with uncertainties of 50% to 70%) predicted using the light cone formalism but are consistent with calculations using the NRQCD factorization approach.Comment: 7 pages, 4 figures, 1 tabl

    Energy scan of the e+e−→hb(nP)π+π−e^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections and evidence for ΄(11020)\Upsilon(11020) decays into charged bottomonium-like states

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    Using data collected with the Belle detector at the KEKB asymmetric-energy e+e−e^+e^- collider, we measure the energy dependence of the e+e−→hb(nP)π+π−e^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections from thresholds up to 11.02 11.02\,GeV. We find clear ΄(10860)\Upsilon(10860) and ΄(11020)\Upsilon(11020) peaks with little or no continuum contribution. We study the resonant substructure of the ΄(11020)→hb(nP)π+π−\Upsilon(11020) \to h_b(nP)\pi^+\pi^- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb(10610)Z_b(10610) and Zb(10650)Z_b(10650). The relative fraction of these states is loosely constrained by the current data: the hypothesis that only Zb(10610)Z_b(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb(10650)Z_b(10650) is produced is not excluded at a significant level.Comment: 8 pages, 4 figures, submitted to Physical Review Letter

    Search for B+ -> l+ nu gamma decays with hadronic tagging using the full Belle data sample

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    We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full Belle data set of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one B meson in a hadronic decay mode and search for the B+ -> l+ nu gamma decay in the remainder of the event. We observe no significant signal within the phase space of E_gamma^sig > 1 GeV and obtain upper limits of BR(B+ -> e+ nu gamma) mu+ nu gamma) l+ nu gamma) < 3.5 x 10^-6 at 90 % credibility level.Comment: Submitted to Phys. Rev.

    Measurement of e+eâˆ’â†’ÎłÏ‡cJe^+e^- \to \gamma\chi_{cJ} via initial state radiation at Belle

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    The process e+eâˆ’â†’ÎłÏ‡cJe^+e^- \to \gamma\chi_{cJ} (JJ=1, 2) is studied via initial state radiation using 980 fb−1^{-1} of data at and around the ΄(nS)\Upsilon(nS) (nn=1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB asymmetric-energy e+e−e^+e^- collider. No significant signal is observed except from ψ(2S)\psi(2S) decays. Upper limits on the cross sections between s=3.80\sqrt{s}=3.80 and 5.56 GeV5.56~{\rm GeV} are determined at the 90% credibility level, which range from few pb to a few tens of pb. We also set upper limits on the decay rate of the vector charmonium [ψ(4040\psi(4040), ψ(4160)\psi(4160), and ψ(4415)\psi(4415)] and charmoniumlike [Y(4260)Y(4260), Y(4360)Y(4360), and Y(4660)Y(4660)] states to ÎłÏ‡cJ\gamma\chi_{cJ}.Comment: Accepted by PR

    Search for Λc+→ϕpπ0\Lambda_c^+\to\phi p \pi^0 and branching fraction measurement of Λc+→K−π+pπ0\Lambda_c^+\to K^-\pi^+ p \pi^0

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    We have searched for the Cabibbo-suppressed decay Λc+→ϕpπ0\Lambda_c^+\to\phi p\pi^0 in e+e−e^+e^- collisions using a data sample corresponding to an integrated luminosity of 915 fb−1\rm fb^{-1}. The data were collected by the Belle experiment at the KEKB e+e−e^+e^- asymmetric-energy collider running at or near the ΄(4S)\Upsilon(4S) and ΄(5S)\Upsilon(5S) resonances. No significant signal is observed, and we set an upper limit on the branching fraction of B(Λc+→ϕpπ0)<15.3×10−5\mathcal{B}(\Lambda_c^+\to \phi p\pi^0) <15.3\times10^{-5} at 90% confidence level. The contribution for nonresonant Λc+→K+K−pπ0\Lambda_c^+\to K^+K^- p\pi^0 decays is found to be consistent with zero and the corresponding upper limit on its branching fraction is set to be B(Λc+→K+K−pπ0)NR<6.3×10−5\mathcal{B}(\Lambda_c^+\to K^+K^-p\pi^0)_{\rm NR} <6.3\times10^{-5} at 90% confidence level. We also measure the branching fraction for the Cabibbo-favored decay Λc+→K−π+pπ0\Lambda_c^+\to K^-\pi^+p\pi^0; the result is B(Λc+→K−π+pπ0)=(4.42±0.05 (stat.)±0.12 (syst.)±0.16 (BNorm))%\mathcal{B}(\Lambda_c^+\to K^-\pi^+p\pi^0)= (4.42\pm0.05\, (\rm stat.) \pm 0.12\, (\rm syst.) \pm 0.16\, (\mathcal{B}_{\rm Norm}))\%, which is the most precise measurement to date. Finally, we have searched for an intermediate hidden-strangeness pentaquark decay Ps+→ϕpP^+_s\to\phi p. We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of B(Λc+→Ps+π0)×B(Ps+→ϕp)<8.3×10−5{\cal B}(\Lambda_c^+\to P^+_s \pi^0)\times {\cal B}(P^+_s\to\phi p) <8.3\times 10^{-5} at 90% confidence level.Comment: 8 pages, 5 figures, 1 table, minor text change in version
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