15 research outputs found

    Complete Genome Sequence of a bla OXA-58 -Producing Acinetobacter baumannii Strain Isolated from a Mexican Hospital

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    ABSTRACT In this study, we present the complete genome sequence of a blaOXA-58- producing Acinetobacter baumannii strain, sampled from a Mexican hospital and not related to the international clone

    Tracking of charged particles with nanosecond lifetimes at LHCb

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    A method is presented to reconstruct charged particles with lifetimes between 10 ps and 10 ns, which considers a combination of their decay products and the partial tracks created by the initial charged particle. Using the Ξ−\Xi^- baryon as a benchmark, the method is demonstrated with simulated events and proton-proton collision data at s=13\sqrt{s}=13 TeV, corresponding to an integrated luminosity of 2.0 fb−1{}^{-1} collected with the LHCb detector in 2018. Significant improvements in the angular resolution and the signal purity are obtained. The method is implemented as part of the LHCb Run 3 event trigger in a set of requirements to select detached hyperons. This is the first demonstration of the applicability of this approach at the LHC, and the first to show its scaling with instantaneous luminosity

    Transverse polarisation measurement of Λ\Lambda hyperons in ppNe collisions at sNN\sqrt{s_{NN}}=68.4 GeV with the LHCb detector

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    A measurement of the transverse polarization of the Λ\Lambda and Λˉ\bar{\Lambda}hyperons in ppNe fixed-target collisions at sNN\sqrt{s_{NN}}=68.4 GeV is presented using data collected by the LHCb detector. The polarization is studied using the decay Λ→pπ−\Lambda \rightarrow p \pi^- together with its charge conjugated process, the integrated values measured are PΛ=0.029±0.019 (stat)±0.012 (syst) , P_{\Lambda} = 0.029 \pm 0.019 \, (\rm{stat}) \pm 0.012 \, (\rm{syst}) \, , PΛˉ=0.003±0.023 (stat)±0.014 (syst)  P_{\bar{\Lambda}} = 0.003 \pm 0.023 \, (\rm{stat}) \pm 0.014 \,(\rm{syst}) \, Furthermore, the results are shown as a function of the Feynman xx variable, transverse momentum, pseudorapidity and rapidity of the hyperons, and are compared with previous measurements.A measurement of the transverse polarization of the Λ\Lambda and Λˉ\bar{\Lambda} hyperons in ppNe fixed-target collisions at sNN\sqrt{s_{NN}} = 68.4 GeV is presented using data collected by the LHCb detector. The polarization is studied using the decay Λ→pπ−\Lambda \rightarrow p \pi^- together with its charge conjugated process, the integrated values measured are PΛ=0.029±0.019 (stat)±0.012 (syst) , P_{\Lambda} = 0.029 \pm 0.019 \, (\rm{stat}) \pm 0.012 \, (\rm{syst}) \, , PΛˉ=0.003±0.023 (stat)±0.014 (syst) . P_{\bar{\Lambda}} = 0.003 \pm 0.023 \, (\rm{stat}) \pm 0.014 \,(\rm{syst}) \,. Furthermore, the results are shown as a function of the Feynman~xx~variable, transverse momentum, pseudorapidity and rapidity of the hyperons, and are compared with previous measurements

    Tracking of charged particles with nanosecond lifetimes at LHCb

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    International audienceA method is presented to reconstruct charged particles with lifetimes between 10 ps and 10 ns, which considers a combination of their decay products and the partial tracks created by the initial charged particle. Using the Ξ−\Xi^- baryon as a benchmark, the method is demonstrated with simulated events and proton-proton collision data at s=13\sqrt{s}=13 TeV, corresponding to an integrated luminosity of 2.0 fb−1{}^{-1} collected with the LHCb detector in 2018. Significant improvements in the angular resolution and the signal purity are obtained. The method is implemented as part of the LHCb Run 3 event trigger in a set of requirements to select detached hyperons. This is the first demonstration of the applicability of this approach at the LHC, and the first to show its scaling with instantaneous luminosity

    Search for time-dependent CPCP violation in D0→π+π−π0D^0 \rightarrow \pi^+ \pi^- \pi^0 decays

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    International audienceA measurement of time-dependent CPCP violation in D0→π+π−π0D^0 \rightarrow \pi^+ \pi^- \pi^0 decays using a pppp collision data sample collected by the LHCb experiment in 2012 and from 2015 to 2018, corresponding to an integrated luminosity of 7.7 fb−1\,\mathrm{fb}^{-1}, is presented. The initial flavour of each D0D^0 candidate is determined from the charge of the pion produced in the D∗(2010)+→D0π+D^*(2010)^+ \rightarrow D^0 \pi^+ decay. The decay D0→K−π+π0D^0 \rightarrow K^- \pi^+ \pi^0 is used as a control channel to validate the measurement procedure. The gradient of the time-dependent CPCP asymmetry, ΔY\Delta Y, in D0→π+π−π0D^0 \rightarrow \pi^+ \pi^- \pi^0 decays is measured to be \begin{equation*} \Delta Y = (-1.3 \pm 6.3 \pm 2.4) \times 10^{-4}, \end{equation*} where the first uncertainty is statistical and the second is systematic, which is compatible with CPCP conservation

    Measurement of the branching fraction ratios R(D+)R(D^+) and R(D∗+)R(D^{*+}) using muonic τ\tau decays

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    The branching fraction ratios of B‟0→D+τ−Μ‟τ\kern 0.18em \overline{\kern -0.18em B}{}^0\to D^+\tau^-\overline{\nu}_{\tau} and B‟0→D∗+τ−Μ‟τ\kern 0.18em \overline{\kern -0.18em B}{}^0\to D^{*+}\tau^-\overline{\nu}_{\tau} decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of 2.0 fb−1^{-1} collected by the LHCb experiment in proton-proton collisions at s=13 TeV\sqrt{s} = 13\,\text{TeV}. The reconstructed final states are formed by combining D+D^+ mesons with τ−→Ό−Μ‟ΌΜτ\tau^-\to\mu^-\overline{\nu}_{\mu}\nu_{\tau} candidates, where the D+D^+ is reconstructed via the D+→K−π+π+D^+\to K^-\pi^+\pi^+ decay. The results are \begin{align*} R(D^{+}) &= 0.249 \pm 0.043 \pm 0.047, \\ R(D^{*+}) &= 0.402 \pm 0.081\pm 0.085, \end{align*} where the first uncertainties are statistical and the second systematic. The two measurements have a correlation coefficient of −0.39-0.39 and are compatible with the Standard Model.The branching fraction ratios of B‟0→D+τ−Μ‟τ\overline{B}^0\to D^+\tau^-\overline{\nu}_{\tau} and B‟0→D∗+τ−Μ‟τ\overline{B}^0\to D^{*+}\tau^-\overline{\nu}_{\tau} decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of 2.0 fb−1^{-1} collected by the LHCb experiment in proton-proton collisions at s=13\sqrt{s} = 13 TeV. The reconstructed final states are formed by combining D+D^+ mesons with τ−→Ό−Μ‟ΌΜτ\tau^-\to\mu^-\overline{\nu}_{\mu}\nu_{\tau} candidates, where the D+D^+ is reconstructed via the D+→K−π+π+D^+\to K^-\pi^+\pi^+ decay. The results are \begin{align*} R(D^{+}) &= 0.249 \pm 0.043 \pm 0.047, R(D^{*+}) &= 0.402 \pm 0.081\pm 0.085, \end{align*} where the first uncertainties are statistical and the second systematic. The two measurements have a correlation coefficient of −0.39-0.39 and are compatible with the Standard Model

    Search for the lepton-flavor violating decay Bs0→ϕΌ±τ∓B^0_s\to\phi\mu^\pm\tau^\mp

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    International audienceA search for the lepton-flavor violating decays Bs0→ϕΌ±τ∓B^0_s\to\phi\mu^\pm\tau^\mp is presented, using a sample of proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb−19\,\text{fb}^{-1}. The τ\tau leptons are selected using decays with three charged pions. No significant excess is observed, and an upper limit on the branching fraction is determined to be B(Bs0→ϕΌ±τ∓)<1.0×10−5{\cal B}( B^0_s\to\phi\mu^\pm\tau^\mp) < 1.0\times 10^{-5} at 90% confidence level

    Comprehensive analysis of local and nonlocal amplitudes in the B0→K∗0ÎŒ+Ό−B^0 \to K^{*0} \mu^+\mu^- decay

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    A comprehensive study of the local and nonlocal amplitudes contributing to the decay B0→K∗0(→K+π−)ÎŒ+Ό−B^0\rightarrow K^{*0}(\to K^+\pi^-) \mu^+\mu^- is performed by analysing the phase-space distribution of the decay products. The analysis is based on pppp collision data corresponding to an integrated luminosity of 8.4fb−1^{-1} collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient C9C_9, responsible for vector dimuon currents, exhibits a 2.1σ2.1\sigma deviation from the Standard Model expectation. The Wilson Coefficients C10C_{10}, C9â€ČC_{9}' and C10â€ČC_{10}' are all in better agreement than C9C_{9} with the Standard Model and the global significance is at the level of 1.5σ1.5\sigma. The model used also accounts for nonlocal contributions from B0→K∗0[τ+τ−→Ό+Ό−]B^{0}\to K^{*0}\left[\tau^+\tau^-\to \mu^+\mu^-\right] rescattering, resulting in the first direct measurement of the bsττb s\tau\tau vector effective-coupling C9τC_{9\tau}.A comprehensive study of the local and nonlocal amplitudes contributing to the decay B0→K∗0(→K+π−)ÎŒ+Ό−B^0\rightarrow K^{*0}(\to K^+\pi^-) \mu^+\mu^- is performed by analysing the phase-space distribution of the decay products. The analysis is based on \proton\proton collision data corresponding to an integrated luminosity of 8.4fb−1^{-1} collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient C9C_9, responsible for vector dimuon currents, exhibits a 2.1σ2.1\sigma deviation from the Standard Model expectation. The Wilson Coefficients C10C_{10}, C9â€ČC_{9}' and C10â€ČC_{10}' are all in better agreement than C9C_{9} with the Standard Model and the global significance is at the level of 1.5σ1.5\sigma. The model used also accounts for nonlocal contributions from B0→K∗0[τ+τ−→Ό+Ό−]B^{0}\to K^{*0}\left[\tau^+\tau^-\to \mu^+\mu^-\right] rescattering, resulting in the first direct measurement of the bsττb s\tau\tau vector effective-coupling C9τC_{9\tau}

    Tracking of charged particles with nanosecond lifetimes at LHCb

    No full text
    International audienceA method is presented to reconstruct charged particles with lifetimes between 10 ps and 10 ns, which considers a combination of their decay products and the partial tracks created by the initial charged particle. Using the Ξ−\Xi^- baryon as a benchmark, the method is demonstrated with simulated events and proton-proton collision data at s=13\sqrt{s}=13 TeV, corresponding to an integrated luminosity of 2.0 fb−1{}^{-1} collected with the LHCb detector in 2018. Significant improvements in the angular resolution and the signal purity are obtained. The method is implemented as part of the LHCb Run 3 event trigger in a set of requirements to select detached hyperons. This is the first demonstration of the applicability of this approach at the LHC, and the first to show its scaling with instantaneous luminosity

    Search for time-dependent CPCP violation in D0→π+π−π0D^0 \rightarrow \pi^+ \pi^- \pi^0 decays

    No full text
    International audienceA measurement of time-dependent CPCP violation in D0→π+π−π0D^0 \rightarrow \pi^+ \pi^- \pi^0 decays using a pppp collision data sample collected by the LHCb experiment in 2012 and from 2015 to 2018, corresponding to an integrated luminosity of 7.7 fb−1\,\mathrm{fb}^{-1}, is presented. The initial flavour of each D0D^0 candidate is determined from the charge of the pion produced in the D∗(2010)+→D0π+D^*(2010)^+ \rightarrow D^0 \pi^+ decay. The decay D0→K−π+π0D^0 \rightarrow K^- \pi^+ \pi^0 is used as a control channel to validate the measurement procedure. The gradient of the time-dependent CPCP asymmetry, ΔY\Delta Y, in D0→π+π−π0D^0 \rightarrow \pi^+ \pi^- \pi^0 decays is measured to be \begin{equation*} \Delta Y = (-1.3 \pm 6.3 \pm 2.4) \times 10^{-4}, \end{equation*} where the first uncertainty is statistical and the second is systematic, which is compatible with CPCP conservation
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