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At least 1,333 records · Page 74
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DOE OSTI2012

Measurement of Z boson Production in Pb+Pb Collisions at s N N = 2.76 TeV with the ATLAS Detector

CERN-LHC. Measurements of the PT and rapidity distributions of Z bosons produced in Lead-Lead collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV. The data sample has 1995 Z boson candidates from the 2011 heavy-ion run with a total integrated luminosity of 0.15 nb-1. The electron and muon decay channels of the Z boson are found to be consistent and combined results are presented. In addition to the rapidity and PT distributions in different centrality regions, the centrality (Npart) dependence of the Z boson yield divided by the mean number of collisions, Ncoll, is presented.

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DOE OSTI2012

Search for new phenomena in events with three charged leptons at / s q r t s = 7 TeV with the ATLAS detector

CERN-LHC. Measurement of the properties of events with 3 or more charged leptons produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample used has a total integrated luminosity of 4.6 fb-1 collected in 2011. The events are required to contain at least two electrons or muons, while the third lepton can be either an additional electron or muon, or a hadronically decaying tau lepton. Events are catagorized by the presence or absence of a reconstructed tau-lepton or a Z-boson candidate decaying into leptons. As well as the fiducial efficiencies the resuts are given as upper limits on event yields from non-SM processes producing at least 3 prompt, isolated leptons, given as functions of the lower bounds on several kinematic variables.

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DOE OSTI2013

Search for long-lived, multi-charged particles in pp collisions at s =7 TeV using the ATLAS detector

CERN-LHC. Measurements of the upper limits of cross sections for the production of highly ionising, penetrating particles with electric charges, |q|, from 2e to 6e in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, collected during the 2011 running period, have an integrated luminosity of 4.4 fb-1. The observed upper limits are present together with the expected limits. Also shown are the rapidly falling cross sections from the Drell-Yan model.

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DOE OSTI2012

Search for light top squark pair production in final states with leptons and b − jets with the ATLAS detector in s = 7 TeV proton-proton collisions

CERN-LHC. Study of events from proton-proton interactions at a centre-of-mass energy of 7 TeV which have final states comprising exclusively one or two leptons (either electrons or muons), large missing transverse momentum, light flavour jets and b-jets. The data sample used has an integrated luminosity of 4.7 fb-1. The data are analysed in the framework of MSSM assuming the top squark decays exclusively to a chargino and b-quark. The data is divided into three signal regions, one (1LSR) requiring only one lepton with two light-quark jets and 2 b-jets, and two (2LSR1 and 2LSR2) requiring only two leptons and two leading jets with different requirements on the minimum energy and invariant mass of the specific subsystem from the hard-scattering process. The reader is refered to the text of the paper for more details.

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DOE OSTI2012

Measurement of angular correlations in Drell-Yan lepton pairs to probe Z/gamma* boson transverse momentum at sqrt(s)=7 TeV with the ATLAS detector

CERN-LHC. Measurements of the PHI* distributions of di-electron and di-muon Drell-Yan pairs produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample has an integrated luminosity of 4.6 fb-1. Normalised differential PHI* distributions are presented within the fiducial region of the leptons corrected to three levels, Born, dressed and bare, for QED FSR. The data are presented for di-electron and di-muons separately as well as combined, and also in three regions of rapidity as well as overall. For details of the variables see the text of the article. UPDATE (05 JAN 2015): corrected columns 2,3,4 of Tables 2,3,5,6 due to a bug fixed for bare and dressed cross sections in y-ranges; Table 4, value of the very last bin of the born dimuon, y>1.6, phi*=2.522-3.277 corrected (typo error).

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DOE OSTI2013

Measurement of the high-mass Drell--Yan differential cross-section in pp collisions at sqrt(s)=7 TeV with the ATLAS detector

CERN-LHC. Based on an integrated luminosity of 4.9 /fb, the differential cross-section in the Z/gamma* to e+e- channel is measured with the ATLAS detector as a function of the invariant mass, Mee, in the range 116 < Mee < 1500 GeV, for a fiducial region in which both the electron and the positron have transverse momentum pT > 25 GeV and absolute pseudorapidity |eta| < 2.5.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for third generation scalar leptoquarks in pp collisions at s = 7 TeV with the ATLAS detector

CERN-LHC. Study of events with final states consisting of one electron or muon with large PT, one high-PT hadronically decaying tau, missing ET from the tau decays, and two high-PT jets, produced in proton-proton collisions at a centre-of-lass enegy of 7 TeV. The data sample used has an integraterd luminosity of 4.7 fb-1 collected during 2011. The data are used to set limits on the production of pairs of 3rd generation leptoquarks which decay in a tau plus b-quark with an assumed branching ratio of 100% with only the specific lepton-hadron decay mode of the tau being sought after here. The limits are shown separately for the electron and muon decay modes of the tau and for the combined two modes combined.

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DOE OSTI2013

Measurement of the differential cross-section of B + meson production in pp collisions at s = 7 TeV at ATLAS

CERN-LHC. The production cross section of B+ mesons is measured as a function of transverse momentum and rapidity in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample used has an integrated luminosity of 2.4 fb-1, with an uncertainty of 1.8%, with results covering the PT range from 9 GeV to 120 GeV and |y| < 2.25.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the inclusive jet cross section in pp collisions at sqrt(s)=2.76 TeV and comparison to the inclusive jet cross section at sqrt(s)=7 TeV using the ATLAS detector

CERN-LHC. This paper reports the measurement of inclusive jet cross sections in proton-proton collisions at a centre-of-mass energy of 2.76 TeV using a data sample of integrated luminosity of 0.20 pb-1 collected in 2011. Jets are identified using the anti-kt algorithm with two radius parameters (0.4 and 0.6). The cross sections are presented as a function of the jet transverse momentum and rapidity covering jets from 20-430 GeV in transverse momentum and |rapidity| < 4.4. The data are also compared with previous ATLAS 7 TeV cross sections as functions of PT and XT. The main tables below show the results correlated and uncorrelated systematic errors individually combined, as presented in the plots in the paper. The first table below gives access to the complete tables with the various sources of systematic error individually presented. Correlations over the rapidity bins and to the 7 TeV data are shown in table 1 of the paper and repeated below.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measurement of W + W &#x2212; production in pp collisions at s =7 TeV with the ATLAS detector and limits on anomalous WWZ and WWγ couplings

CERN-LHC. Measurements of the cross section for W+W- production in proton proton collisions at a centre-of mass energy of 7 TeV. The data sample used, collected during 2011, has a total integrated luminosity of 4.6 fb-1 with 1325 candidate events in the double leptonic decay final state with electrons, muons and missing transverse momentum. The total cross section is presented together with fiducial cross sections in a phase space region, defined for each decay channel.

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DOE OSTI2013

Search for new phenomena in final states with large jet multiplicities and missing transverse momentum at s =8 TeV proton-proton collisions using the ATLAS experiment

CERN-LHC. Results are presented of a search that looks for new particles decaying to large numbers (7 to greater or equal to 10) of jets, missing transverse momentum and no isolated electrons or muons. This analysis uses 20.3/fb of pp collision data at sqrt(s)=8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The sensitivity of the search is enhanced by considering the number of b-tagged jets and the scalar sum of masses of large-radius jets in an event. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of various simplified supersymmetry-inspired models where gluinos are pair produced, as well as a mSUGRA/CMSSM model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of about 25 fb-1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for nonpointing photons in the diphoton and E T m i s s final state in s =7 TeV proton-proton collisions using the ATLAS detector

CERN-LHC. Study of events with a final state comprising two photons and missing transverse energy in proton-proton interactions at a centre-of-mass energy of 7 TeV using a data sample, collected in 2011, with an integrated luminosity of 4.8 fb-1. The analysis is focussed on a search for photons originating in the decay of neutral long-lived particles, exploiting the electromagnetic calorimeters ability to make measurements of the flight direction of the photons as well as excellent time resolution. Results are compared with Standard Model (SM ) expections as well as the predictions from GMSB models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurements of W &#x3B3; and Z &#x3B3; production in p p collisions at s =7 TeV with the ATLAS detector at the LHC

CERN-LHC. Measurements of the cross sections for Wgamma and Zgamma production in proton proton collisions at a centre-of mass energy of 7 TeV. The integrated and differential fiducial cross sections for the production of a W or Z boson in association with a high-energy photon are measured at sqrt(s) = 7 TeV. The analyses use a data sample with an integrated luminosity of 4.6 fb^{-1} collected by the ATLAS detector during the 2011 LHC data-taking period. Events are selected using leptonic decays of the W and Z bosons (W(e nu, mu nu) and Z(e+ e-, mu+ mu-, nu nubar)) with the requirement of an associated isolated photon. The data are used to test the electroweak sector of the Standard Model and search for evidence for new phenomena. The measurements are used to probe the anomalous WWgamma, ZZgamma and Zgammagamma triple-gauge-boson couplings and to search for the production of vector resonances decaying to Zgamma and Wgamma.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of dijet cross sections in p p collisions at 7 TeV centre-of-mass energy using the ATLAS detector

CERN-LHC. Double-differential dijet cross sections measured in pp collisions at the LHC with a 7 TeV centre-of-mass energy are presented as functions of dijet mass and rapidity separation of the two highest-pT jets. These measurements are obtained using data corresponding to an integrated luminosity of 4.5 fb^-1, recorded by the ATLAS detector in 2011. The data are corrected for detector effects so that cross sections are presented at the particle level. Cross sections are measured up to 5 TeV dijet mass using jets reconstructed with the anti-kt algorithm for values of the jet radius parameter of 0.4 and 0.6.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measurements of top quark pair relative differential cross-sections with ATLAS in p p collisions at s = 7 TeV

CERN-LHC. Measurements are presented of differential cross sections for top quark pair production in pp collisions at sqrt(s) = 7 TeV relative to the total inclusive top quark pair production cross section. A data sample of 2.05 fb^-1 recorded by the ATLAS detector between March and August 2011 at the Large Hadron Collider is used. Relative differential cross sections are derived as a function of the invariant mass, the transverse momentum and the rapidity of the top quark pair system. Events are selected in the lepton (electron or muon) + jets channel. The background-subtracted differential distributions are corrected for detector effects and normalized to the total inclusive top quark pair production cross section. The measurement uncertainties range typically between 10% and 20% and are generally dominated by systematic effects.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for new phenomena in photon+jet events collected in proton--proton collisions at sqrt(s) = 8 TeV with the ATLAS detector

CERN-LHC. A model-independent search is made for the production of new resonances in photon + jet events using 20 fb^-1 of proton-proton LHC data recorded with the ATLAS detector in 2012 at a centre-of-mass energy of sqrt(s) = 8 TeV. The photon + jet mass distribution is compared to a background model fit from data; no significant deviation from the background-only hypothesis is found. Limits are set at 95% credibility level on generic Gaussian-shaped signals and two benchmark phenomena beyond the Standard Model: non-thermal quantum black holes and excited quarks. Non-thermal quantum black holes are excluded below masses of 4.6 TeV and excited quarks are excluded below masses of 3.5 TeV.

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