A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb[Formula: see text] of proton-proton collision data at [Formula: see text] [Formula: see text] collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant.
View Article and Find Full Text PDFThe integrated elliptic flow of charged particles produced in Pb+Pb collisions at [Formula: see text] TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, [Formula: see text], was measured in the pseudorapidity range [Formula: see text] with the event-plane method. In order to include tracks with very low transverse momentum [Formula: see text], thus reducing the uncertainty in [Formula: see text] integrated over [Formula: see text], a [Formula: see text] data sample recorded without a magnetic field in the tracking detectors is used.
View Article and Find Full Text PDFEur Phys J C Part Fields
July 2014
Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at [Formula: see text] TeV and corresponding to an integrated luminosity of 4.7 fb[Formula: see text].
View Article and Find Full Text PDFA measurement is presented of the [Formula: see text] production cross section at [Formula: see text] = 7 TeV using [Formula: see text] collision data corresponding to an integrated luminosity of 383 [Formula: see text], collected with the ATLAS experiment at the LHC. Selection of [Formula: see text](1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, [Formula: see text], and rapidity, [Formula: see text], of the [Formula: see text](1020) meson in the fiducial region 500 [Formula: see text] 1200 MeV, [Formula: see text] 0.
View Article and Find Full Text PDFA search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the [Formula: see text] boson mass, jets tagged as originating from [Formula: see text]-quarks and missing transverse momentum. The analysis is performed with proton-proton collision data at [Formula: see text] collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb[Formula: see text].
View Article and Find Full Text PDFEur Phys J C Part Fields
November 2014
ATLAS measurements of the azimuthal anisotropy in lead-lead collisions at [Formula: see text] TeV are shown using a dataset of approximately 7 [Formula: see text]b[Formula: see text] collected at the LHC in 2010. The measurements are performed for charged particles with transverse momenta [Formula: see text] GeV and in the pseudorapidity range [Formula: see text]. The anisotropy is characterized by the Fourier coefficients, [Formula: see text], of the charged-particle azimuthal angle distribution for [Formula: see text]-4.
View Article and Find Full Text PDFEur Phys J C Part Fields
November 2014
This paper presents the performance of the ATLAS muon reconstruction during the LHC run with [Formula: see text] collisions at [Formula: see text]-8 TeV in 2011-2012, focusing mainly on data collected in 2012. Measurements of the reconstruction efficiency and of the momentum scale and resolution, based on large reference samples of [Formula: see text], [Formula: see text] and [Formula: see text] decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided.
View Article and Find Full Text PDFAdditional jet activity in dijet events is measured using [Formula: see text] collisions at ATLAS at a centre-of-mass energy of [Formula: see text], for jets reconstructed using the [Formula: see text] algorithm with radius parameter [Formula: see text]. This is done using variables such as the fraction of dijet events without an additional jet in the rapidity interval bounded by the dijet subsystem and correlations between the azimuthal angles of the dijet s. They are presented, both with and without a veto on additional jet activity in the rapidity interval, as a function of the scalar average of the transverse momenta of the dijet s and of the rapidity interval size.
View Article and Find Full Text PDFThe inclusive top quark pair ([Formula: see text]) production cross-section [Formula: see text] has been measured in proton-proton collisions at [Formula: see text] and [Formula: see text] with the ATLAS experiment at the LHC, using [Formula: see text] events with an opposite-charge [Formula: see text] pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 [Formula: see text] and the 2012 8 TeV dataset of 20.
View Article and Find Full Text PDFThe development of orally active pulmonary vasodilators has been a major breakthrough in the treatment of pulmonary arterial hypertension (PAH). Orally active medications greatly enhanced patient access to PAH treatment and increased an interest in the diagnosis and treatment of this disease that still continues. Four different orally active drugs are currently available for the treatment of PAH and several more are undergoing evaluation.
View Article and Find Full Text PDFBackground: Submassive pulmonary embolism (PE) has a low mortality rate but can degrade functional capacity.
Objective: The present study aims to provide rationale, methodology, and initial findings of a multicentre, randomised trial of fibrinolysis for PE that used a composite end-point, including quality of life measures.
Methods: This investigator-initiated study was funded by a contract between a corporate partner and the investigator's hospital (the prime site).
Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δφ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δφ dependence of jet yields in 0.14 nb(-1) of √(s(NN))=2.
View Article and Find Full Text PDFBackground: Prediction scores for pretest probability of pulmonary embolism (PE) validated in outpatient settings are occasionally used in the intensive care unit (ICU).
Objective: To evaluate the correlation of Geneva and Wells scores with adjudicated categories of PE in ICU patients.
Methods: In a randomized trial of thromboprophylaxis, patients with suspected PE were adjudicated as possible, probable or definite PE.
Female sex is a risk factor for pulmonary arterial hypertension (PAH), yet females have better survival than males. We sought to determine if sex was associated with baseline haemodynamics in subjects with PAH, and whether age modified these relationships. We conducted a pooled analysis from 11 randomised trials submitted to the US Food and Drug Administration.
View Article and Find Full Text PDFAims: Circulating endothelium-derived extracellular vesicles (EV) levels are altered in pulmonary arterial hypertension (PAH) but whether they are biomarkers of cellular injury or participants in disease pathogenesis is unknown. Previously, we found that lung-derived EVs (LEVs) induce bone marrow-derived progenitor cells to express lung-specific mRNA and protein. In this study, we sought to determine whether LEV or plasma-derived EV (PEV) alter pulmonary vascular endothelial or marrow progenitor cell phenotype to induce pulmonary vascular remodelling.
View Article and Find Full Text PDFAm J Respir Crit Care Med
September 2013
Nitric oxide (NO) signaling plays a major role in modulating vascular tone and remodeling in the pulmonary circulation, but its role in the pathogenesis of pulmonary vascular diseases is still not completely understood. Numerous abnormalities of NO synthesis and signaling have been identified in animal models of pulmonary vascular disease and in humans with pulmonary hypertension. Many of these abnormalities have become targets of new therapies for the treatment of pulmonary hypertension.
View Article and Find Full Text PDFTwo-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the transverse energy (ΣE(T)(Pb)) summed over 3.
View Article and Find Full Text PDFIn 3 studies we explored when 3-year-olds would imitate novel words in utterances produced by adult speakers. Child and experimenter took turns in requesting objects from a game master. The experimenter always went first and always preceded the object's familiar name with a novel adjective (e.
View Article and Find Full Text PDFThe ATLAS experiment has observed 1995 Z boson candidates in data corresponding to 0.15 nb(-1) of integrated luminosity obtained in the 2011 LHC Pb+Pb run at sqrt[s(NN)]=2.76 TeV.
View Article and Find Full Text PDFResults of a search for new phenomena in events with an energetic photon and large missing transverse momentum in proton-proton collisions at sqrt[s] = 7 TeV are reported. Data collected by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 4.6 fb(-1) are used.
View Article and Find Full Text PDFThis Letter presents a search for magnetic monopoles with the ATLAS detector at the CERN Large Hadron Collider using an integrated luminosity of 2.0 fb(-1) of pp collisions recorded at a center-of-mass energy of sqrt[s]=7 TeV. No event is found in the signal region, leading to an upper limit on the production cross section at 95% confidence level of 1.
View Article and Find Full Text PDFEur Phys J C Part Fields
August 2013
The luminosity calibration for the ATLAS detector at the LHC during collisions at [Formula: see text] in 2010 and 2011 is presented. Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the collisions at [Formula: see text]. A luminosity uncertainty of [Formula: see text] is obtained for the 47 pb of data delivered to ATLAS in 2010, and an uncertainty of [Formula: see text] is obtained for the 5.
View Article and Find Full Text PDFA search for a charged Higgs boson () in [Formula: see text] decays is presented, where one of the top quarks decays via →, followed by → two jets ([Formula: see text]). The other top quark decays to , where the boson then decays into a lepton (/) and a neutrino. The data were recorded in collisions at [Formula: see text] by the ATLAS detector at the LHC in 2011, and correspond to an integrated luminosity of 4.
View Article and Find Full Text PDFEur Phys J C Part Fields
May 2013
A measurement of splitting scales, as defined by the clustering algorithm, is presented for final states containing a boson produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing bosons decaying to electrons or muons.
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