| 1. |
- Sparv, David, et al.
(author)
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The Analgesic Effect of Oxygen in Suspected Acute Myocardial Infarction : A Substudy of the DETO2X-AMI Trial
- 2018
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In: JACC: Cardiovascular Interventions. - : Elsevier BV. - 1936-8798 .- 1876-7605. ; 39, s. 546-546
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Journal article (peer-reviewed)abstract
- Objectives: In this substudy of the DETO2X-AMI (An Efficacy and Outcome Study of Supplemental Oxygen Treatment in Patients With Suspected Myocardial Infarction) trial, the authors aimed to assess the analgesic effect of moderate-flow oxygen supplementation in patients with suspected acute myocardial infarction (AMI) treated with percutaneous coronary intervention (PCI) and to study the effect of oxygen supplementation on the use of opiates and sedatives during PCI. Background: Routine oxygen in normoxemic patients with AMI does not provide clinical benefit. However, oxygen may relieve ischemic pain. Methods: Patients were randomly allocated to oxygen or ambient air according to the main study protocol. After PCI, peak level of pain during PCI was measured by the Visual Analogue Scale. The total amount of opiates and sedatives was reported. Results: A total of 622 patients were enrolled: 330 in the oxygen group and 292 in the ambient air group. There was no significant difference in peak level of pain (oxygen 4.0 [1.0 to 6.0] vs. air 3.0 [0.6 to 6.0]; p = 0.37), use of opiates (mg) (oxygen 0.0 [0.0 to 3.0] vs. air 0.0 [0.0 to 3.0]; p = 0.31), or use of sedatives between the groups (median [interquartile range]) (oxygen 2.5 [0.0 to 2.5] vs. air 2.5 [0.0 to 2.5]; p = 0.74). Conclusions: In the present study, the authors did not find any analgesic effect of routine oxygen as compared with ambient air, and no differences in the use of sedatives and opiates during PCI. Our results indicate that moderate-flow oxygen supplementation does not relieve pain in normoxemic patients with suspected AMI undergoing treatment with PCI and should thus not be used for this purpose.
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| 2. |
- Aaboud, M, et al.
(author)
-
Measurement of jet pT correlations in Pb + Pb and pp collisions at sNN=2.76 TeVwith the ATLAS detector
- 2017
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 774, s. 379-402
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Journal article (peer-reviewed)abstract
- Measurements of dijet pT correlations in Pb+Pb and pp collisions at a nucleon–nucleon centre-of-mass energy of sNN=2.76 TeV are presented. The measurements are performed with the ATLAS detector at the Large Hadron Collider using Pb+Pb and pp data samples corresponding to integrated luminosities of 0.14 nb−1 and 4.0 pb−1, respectively. Jets are reconstructed using the anti-kt algorithm with radius parameter values R=0.3 and R=0.4. A background subtraction procedure is applied to correct the jets for the large underlying event present in Pb+Pb collisions. The leading and sub-leading jet transverse momenta are denoted pT1 and pT2. An unfolding procedure is applied to the two-dimensional (pT1,pT2) distributions to account for experimental effects in the measurement of both jets. Distributions of (1/N)dN/dxJ, where xJ=pT2/pT1, are presented as a function of pT1 and collision centrality. The distributions are found to be similar in peripheral Pb+Pb collisions and pp collisions, but highly modified in central Pb+Pb collisions. Similar features are present in both the R=0.3 and R=0.4 results, indicating that the effects of the underlying event are properly accounted for in the measurement. The results are qualitatively consistent with expectations from partonic energy loss models. © 2017 The Author
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| 3. |
- Aaboud, M, et al.
(author)
-
Measurement of lepton differential distributions and the top quark mass in tt¯ production in pp collisions at √s=8 TeV with the ATLAS detector
- 2017
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:11
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Journal article (peer-reviewed)abstract
- This paper presents single lepton and dilepton kinematic distributions measured in dileptonic tt¯ events produced in 20.2fb - 1 of s=8 TeV pp collisions recorded by the ATLAS experiment at the LHC. Both absolute and normalised differential cross-sections are measured, using events with an opposite-charge eμ pair and one or two b-tagged jets. The cross-sections are measured in a fiducial region corresponding to the detector acceptance for leptons, and are compared to the predictions from a variety of Monte Carlo event generators, as well as fixed-order QCD calculations, exploring the sensitivity of the cross-sections to the gluon parton distribution function. Some of the distributions are also sensitive to the top quark pole mass; a combined fit of NLO fixed-order predictions to all the measured distributions yields a top quark mass value of mtpole=173.2±0.9±0.8±1.2 GeV, where the three uncertainties arise from data statistics, experimental systematics, and theoretical sources. © 2017, CERN for the benefit of the ATLAS collaboration.
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| 4. |
- Aaboud, M, et al.
(author)
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Measurements of top-quark pair differential cross-sections in the lepton+jets channel in pp collisions at √s=13 TeV using the ATLAS detector
- 2017
-
In: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; 2017:11
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Journal article (peer-reviewed)abstract
- Measurements of differential cross-sections of top-quark pair production in fiducial phase-spaces are presented as a function of top-quark and tt¯ system kinematic observables in proton-proton collisions at a centre-of-mass energy of s=13 TeV. The data set corresponds to an integrated luminosity of 3.2 fb−1, recorded in 2015 with the ATLAS detector at the CERN Large Hadron Collider. Events with exactly one electron or muon and at least two jets in the final state are used for the measurement. Two separate selections are applied that each focus on different top-quark momentum regions, referred to as resolved and boosted topologies of the tt¯ final state. The measured spectra are corrected for detector effects and are compared to several Monte Carlo simulations by means of calculated χ2 and p-values. © 2017, The Author(s).
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| 5. |
- Aaboud, M, et al.
(author)
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Search for Dark Matter Produced in Association with a Higgs Boson Decaying to b b Using 36 fb-1 of pp Collisions at s =13 TeV with the ATLAS Detector
- 2017
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In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 119:18
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Journal article (peer-reviewed)abstract
- Several extensions of the standard model predict associated production of dark-matter particles with a Higgs boson. Such processes are searched for in final states with missing transverse momentum and a Higgs boson decaying to a bb pair with the ATLAS detector using 36.1 fb-1 of pp collisions at a center-of-mass energy of 13 TeV at the LHC. The observed data are in agreement with the standard model predictions and limits are placed on the associated production of dark-matter particles and a Higgs boson. © 2017 CERN, for the ATLAS Collaboration. Published by the American Physical Society.
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| 6. |
- Aad, G, et al.
(author)
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Beam-induced and cosmic-ray backgrounds observed in the ATLAS detector during the LHC 2012 proton-proton running period
- 2016
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In: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 11:5
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Journal article (peer-reviewed)abstract
- This paper discusses various observations on beam-induced and cosmic-ray backgrounds in the ATLAS detector during the LHC 2012 proton-proton run. Building on published results based on 2011 data, the correlations between background and residual pressure of the beam vacuum are revisited. Ghost charge evolution over 2012 and its role for backgrounds are evaluated. New methods to monitor ghost charge with beam-gas rates are presented and observations of LHC abort gap population by ghost charge are discussed in detail. Fake jets from colliding bunches and from ghost charge are analysed with improved methods, showing that ghost charge in individual radio-frequency buckets of the LHC can be resolved. Some results of two short periods of dedicated cosmic-ray background data-taking are shown; in particular cosmic-ray muon induced fake jet rates are compared to Monte Carlo simulations and to the fake jet rates from beam background. A thorough analysis of a particular LHC fill, where abnormally high background was observed, is presented. Correlations between backgrounds and beam intensity losses in special fills with very high β∗ are studied. © 2016 CERN for the benefit of the ATLAS collaboration.
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| 7. |
- Aad, G, et al.
(author)
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Constraints on non-Standard Model Higgs boson interactions in an effective Lagrangian using differential cross sections measured in the H → γγ decay channel at √s=8 TeV with the ATLAS detector
- 2016
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 753, s. 69-85
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Journal article (peer-reviewed)abstract
- The strength and tensor structure of the Higgs boson's interactions are investigated using an effective Lagrangian, which introduces additional CP-even and CP-odd interactions that lead to changes in the kinematic properties of the Higgs boson and associated jet spectra with respect to the Standard Model. The parameters of the effective Lagrangian are probed using a fit to five differential cross sections previously measured by the ATLAS experiment in the H→γγ decay channel with an integrated luminosity of 20.3 fb−1 at s=8 TeV. In order to perform a simultaneous fit to the five distributions, the statistical correlations between them are determined by re-analysing the H→γγ candidate events in the proton–proton collision data. No significant deviations from the Standard Model predictions are observed and limits on the effective Lagrangian parameters are derived. The statistical correlations are made publicly available to allow for future analysis of theories with non-Standard Model interactions. © 2015 CERN for the benefit of the ATLAS Collaboration.
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| 8. |
- Aad, G., et al.
(author)
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Measurement of exclusive gamma gamma -> l(+)l(-) production in proton-proton collisions at root s=7 TeV with the ATLAS detector
- 2015
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 749, s. 242-261
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Journal article (peer-reviewed)abstract
- This Letter reports a measurement of the exclusive gamma gamma -> l(+)l(-) (l = e, mu) cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of 4.6 fb(-1). For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be sigma(excl)(gamma gamma -> e+e-) = 0.428 +/- 0.035 (stat.) +/- 0.018 (syst.) pbfor a phase-space region with invariant mass of the electron pairs greater than 24GeV, in which both electrons have transverse momentum p(T) > 12 GeV and pseudorapidity vertical bar eta vertical bar < 2.4. For muon pairs with invariant mass greater than 20GeV, muon transverse momentum pT> 10 GeV and pseudorapidity vertical bar eta vertical bar < 2.4, the cross-section is determined to be sigma(excl)(gamma gamma -> mu+mu-) = 0.628 +/- 0.032(stat.) +/- 0.021 (syst.) pb. When proton absorptive effects due to the finite size of the proton are taken into account in the theory calculation, the measured cross-sections are found to be consistent with the theory prediction. (C) 2015 CERN for the benefit of the ATLAS Collaboration. Published by Elsevier B.V.
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| 9. |
- Aad, G, et al.
(author)
-
Measurement of the ZZ production cross section in pp collisions at √s = 13 TeV with the ATLAS detector
- 2016
-
In: Physical Review Letters. - : American Physical Society. - 1079-7114 .- 0031-9007. ; 116:10
-
Journal article (peer-reviewed)abstract
- The ZZ production cross section in proton-proton collisions at 13 TeV center-of-mass energy is measured using 3.2 fb-1 of data recorded with the ATLAS detector at the Large Hadron Collider. The considered Z boson candidates decay to an electron or muon pair of mass 66-116 GeV. The cross section is measured in a fiducial phase space reflecting the detector acceptance. It is also extrapolated to a total phase space for Z bosons in the same mass range and of all decay modes, giving 16.7-2.0+2.2(stat)+0.9-0.7(syst)+1.0-0.7(lumi) pb. The results agree with standard model predictions. © 2016 CERN. Published by the American Physical Society under the terms of the "http://creativecommons.org/licenses/by/3.0/" Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
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| 10. |
- Aad, G, et al.
(author)
-
Performance of b-jet identification in the ATLAS experiment
- 2016
-
In: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 11:4
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Journal article (peer-reviewed)abstract
- The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty. © CERN 2016 for the benefit of the ATLAS collaboration, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl.
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