2,797 research outputs found

    Measurement of the kinematic variables of beauty particles produced in 350 GeV/c π−\pi^--Cu interactions

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    Using a sample of 2626 b\=b events, produced in 350 GeV/c350\,\hbox{GeV}/c π−\pi^- interactions in a copper target, which includes 1313 events where the decays of both BB and B‟\overline{B} are well reconstructed, we measure the differential distributions with respect to xFx_F and pT2p_T^2 as well as some two-particle kinematic variables. We also compare our results with a previous experiment and with predictions based on perturbative QCD

    Azimuthal correlation between beauty particles produced in 350 GeV/c π−\pi^{-}-Cu interactions

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    Using a sample of 10810^8 triggered events, produced in 350 GeV/c350\, \hbox{GeV}/c π−\pi^- interactions in a copper target, we have identified 2626 b\=b events. These include 1313 events where the decays of both BB and B‟\overline{B} are well reconstructed. We measure the azimuthal \hbox{correlation} between beauty particles, and compare our result with predictions based on perturbative QCD

    A concept of the transition radiation detector for a hadron separation in a forward direction of the LHC experiments

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    Studying of hadron production in forward direction at the LHC energy has a great interest both for understanding of the fundamental QCD processes and also in applied areas such as the description of ultra-high energy cosmic particle interactions. The energies of secondary hadrons in such studies almost reach the maximum energy available at the LHC of ∌6 TeV, which corresponds to a Lorentz Îł-factor up to 104 and above. The only effective technique able to identify particles in this range is based on the transition radiation detectors (TRD). Prototypes of such kind of detector were built and tested at the CERN SPS accelerator. Some experimental results obtained in these tests are briefly presented here and compared with Monte Carlo (MC) simulations. MC model demonstrates a good agreement with the experiment. On this basis a concept of a full-scale TRD optimized for the hadron identification in the TeV energy region is proposed. Different particle identification techniques were considered and examined. The expected detector performance to reconstruct secondary hadrons produced in forward direction at the LHC is presented

    Measurements of charmed-meson production in interactions between 350 GeV/c π−\pi^- particles and nuclei

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    Charmed-meson production by 350350~GeV/cc {π−\pi^-} particles incident on copper and tungsten targets has been studied in the WA9292 experiment, performed at the CERN Ωâ€Č\Omega^\prime spectrometer. Results obtained are reported and discussed. Reconstruction of decays from the set D0→K−π+{\rm D}^0 \rightarrow {\rm K}^- \pi^+, D0→K−π−π+π+{\rm D}^0 \rightarrow {\rm K}^- \pi^- \pi^+ \pi^+, D+→K−π+π+{\rm D}^+ \rightarrow {\rm K}^- \pi^+ \pi^+, Ds+→ϕπ+{{\rm D}_{\rm s}}^+ \rightarrow \phi \pi^+ and charge conjugates has yielded a sample of 7280±1087280 \pm 108 charmed mesons, produced with \xf > 0, \langle \xf \rangle = 0.18 and \langle {\pt}^2 \rangle = 1.86~{\rm (GeV/}c{\rm )}^2. Assuming a relationship σ=σ0Aα\sigma = \sigma_0 A^\alpha between the cross-section, σ\sigma, per nucleus of mass AA and the nucleonic cross-section, σ0\sigma_0, the α\alpha value found for the detected charmed particles is 0.95±0.06±0.030.95 \pm 0.06 \pm 0.03. Taking α=1\alpha = 1, the measured cross-sections per nucleon for \xf > 0 production are 7.78±0.14±0.527.78 \pm 0.14 \pm 0.52~ÎŒ\mubarn for D0{\rm D}^0/Dˉ0\bar{\rm D}^0, 3.28±0.08±0.293.28 \pm 0.08 \pm 0.29~ÎŒ\mubarn for D+{\rm D}^+/D−{\rm D}^- and 1.29±0.16±0.331.29 \pm 0.16 \pm 0.33~ÎŒ\mubarn for Ds+{{\rm D}_{\rm s}}^+/Ds−{{\rm D}_{\rm s}}^-. Differential cross-sections with respect to \xf and {\pt}^2 have been determined for the various types of charmed meson, and particle-antiparticle asymmetries have been analysed

    Practical efficacy and safety of Konsilar D24 in patients with hypertension: data from the KONSONANS program

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    Aim. In practice, to evaluate the efficacy, safety and long-term adherence to therapy with a fixed-dose combination of ramipril/indapamide (Konsilar-D24) in patients with grade 1-2 hypertension (HTN) who have not achieved blood pressure (BP) control with prior therapy or have not taken antihypertensive therapy.Material and methods. This multicenter open-label observational program included 524 patients with grade 1-2 HTN who did not take antihypertensive therapy or did not reach the target BP level with mono or dual antihypertensive therapy, as well as patients shifted to Konsilar-D24 therapy no later than two weeks before the start of the program. All patients signed a written informed consent to participate in the program. The safety analysis set includes all patients who have taken at least one dose of a fixed-dose combination of ramipril/indapamide and have visited physician at least once during the program. The effectiveness analysis set included all patients in the safety population who completed the study in accordance with protocol (n=511). Clinical systolic blood pressure (SBP), diastolic BP (DBP) and heart rate were assessed at baseline, as well as at 0,5, 1, 3 and 6 months of treatment. A post hoc subgroup analysis of changes in BP and heart rate was performed depending on age, sex and baseline body mass index.Results. The fixed-dose combination of ramipril with indapamide significantly reduced SBP and DBP after 2-week treatment (-20,9±10,1 mm Hg; pConclusion. Despite the limitations inherent in observational studies, the KONSONANS program has demonstrated high efficacy and safety of fixed-dose combination of ramipril/indapamide taken once a day in hypertensive patients. Ramipril/indapamide fixed-dose combination therapy significantly improved BP control and achieved even lower individual target BP levels in the majority of hypertensive patients

    Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

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    A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

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    The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +cÂŻÂŻ)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−sÂŻÂŻÂŻ quark asymmetry

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal
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