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Träfflista för sökning "WFRF:(Hanagaki K.) srt2:(2013)"

Sökning: WFRF:(Hanagaki K.) > (2013)

  • Resultat 51-60 av 75
  • Föregående 1...2345[6]78Nästa
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51.
  • Aad, G., et al. (författare)
  • Search for pair production of heavy top-like quarks decaying to a high-p(T) W boson and a b quark in the lepton plus jets final state at root s=7 TeV with the ATLAS detector
  • 2013
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier. - 0370-2693 .- 1873-2445. ; 718:4-5, s. 1284-1302
  • Tidskriftsartikel (refereegranskat)abstract
    • A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb(-1) of pp collisions root s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton + jets final state, characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in the t'(t') over bar signal when m(t') greater than or similar to 400 GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t' -> W b) = I, a fourth-generation t' quark with mass lower than 656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass similar to 126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t' -> Wb) versus BR(t' -> Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
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52.
  • Aad, G., et al. (författare)
  • Searches for heavy long-lived sleptons and R-hadrons with the ATLAS detector in pp collisions at root s=7 TeV
  • 2013
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier. - 0370-2693 .- 1873-2445. ; 720:4-5, s. 277-308
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for long-lived particles is performed using a data sample of 4.7 fb(-1) from proton-proton collisions at a centre-of-mass energy. root s = 7 TeV collected by the ATLAS detector at the LHC. No excess is observed above the estimated background and lower limits, at 95% confidence level, are set on the mass of the long-lived particles in different scenarios, based on their possible interactions in the inner detector, the calorimeters and the muon spectrometer. Long-lived staus in gauge-mediated SUSY-breaking models are excluded up to a mass of 300 GeV for tan beta = 5-20. Directly produced long-lived sleptons are excluded up to a mass of 278 GeV. R-hadrons, composites of gluino (stop, sbottom) and light quarks, are excluded up to a mass of 985 GeV (683 GeV, 612 GeV) when using a generic interaction model. Additionally two sets of limits on R-hadrons are obtained that are less sensitive to the interaction model for R-hadrons. One set of limits is obtained using only the inner detector and calorimeter observables, and a second set of limits is obtained based on the inner detector alone. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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53.
  • Aad, G., et al. (författare)
  • Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
  • 2013
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer. - 1434-6044 .- 1434-6052. ; 73:3
  • Tidskriftsartikel (refereegranskat)abstract
    • 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 root 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.
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54.
  • Aad, G., et al. (författare)
  • A search for high-mass resonances decaying to tau(+)tau(-) in pp collisions at root s=7 TeV with the ATLAS detector
  • 2013
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier. - 0370-2693 .- 1873-2445. ; 719:4-5, s. 242-260
  • Tidskriftsartikel (refereegranskat)abstract
    • This Letter presents a search for high-mass resonances decaying into tau(+)tau(-) final states using proton-proton collisions at root s = 7 TeV produced by the Large Hadron Collider. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 4.6 fb(-1). No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z' resonances decaying into tau(+)tau(-) pairs as a function of the resonance mass. As a result, Z' bosons of the Sequential Standard Model with masses less than 1.40 TeV are excluded at 95% credibility. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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55.
  • Aad, G., et al. (författare)
  • ATLAS search for new phenomena in dijet mass and angular distributions using pp collisions at root s=7 TeV
  • 2013
  • Ingår i: Journal of High Energy Physics. - : Springer. - 1029-8479 .- 1126-6708. ; :1
  • Tidskriftsartikel (refereegranskat)abstract
    • Mass and angular distributions of dijets produced in LHC proton-proton collisions at a centre-of-mass energy root s = 7TeV have been studied with the ATLAS detector using the full 2011 data set with an integrated luminosity of 4.8 fb(-1). Dijet masses up to similar to 4.0TeV have been probed. No resonance-like features have been observed in the dijet mass spectrum, and all angular distributions are consistent with the predictions of QCD. Exclusion limits on six hypotheses of new phenomena have been set at 95% CL in terms of mass or energy scale, as appropriate. These hypotheses include excited quarks below 2.83 TeV, colour octet scalars below 1.86TeV, heavy W bosons below 1.68 TeV, string resonances below 3.61 TeV, quantum black holes with six extra space-time dimensions for quantum gravity scales below 4.11 TeV, and quark contact interactions below a compositeness scale of 7.6 TeV in a destructive interference scenario.
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56.
  • Aad, G., et al. (författare)
  • Search for contact interactions and large extra dimensions in dilepton events from pp collisions at root s=7 TeV with the ATLAS detector
  • 2013
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - : American Physical Society. - 1550-2368 .- 1550-7998. ; 87:1
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for nonresonant new phenomena, originating from either contact interactions or large extra spatial dimensions, has been carried out using events with two isolated electrons or muons. These events, produced at the LHC in proton-proton collisions at root s = 7 TeV, were recorded by the ATLAS detector. The data sample, collected throughout 2011, corresponds to an integrated luminosity of 4.9 and 5.0 fb(-1) in the e(+)e(-) and mu(+)mu(-) channels, respectively. No significant deviations from the Standard Model expectation are observed. Using a Bayesian approach, 95% confidence level lower limits ranging from 9.0 to 13.9 TeV are placed on the energy scale of llqq contact interactions in the left-left isoscalar model. Lower limits ranging from 2.4 to 3.9 TeV are also set on the string scale in large extra dimension models. After combining these limits with results from a similar search in the diphoton channel, slightly more stringent limits are obtained. DOI: 10.1103/PhysRevD.87.015010
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57.
  • Aad, G., et al. (författare)
  • Search for extra dimensions in diphoton events from proton-proton collisions at root s=7 TeV in the ATLAS detector at the LHC
  • 2013
  • Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15
  • Tidskriftsartikel (refereegranskat)abstract
    • The large difference between the Planck scale and the electroweak scale, known as the hierarchy problem, is addressed in certain models through the postulate of extra spatial dimensions. A search for evidence of extra spatial dimensions in the diphoton channel has been performed using the full set of proton-proton collisions at root s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. This dataset corresponds to an integrated luminosity of 4.9 fb(-1). The diphoton invariant mass spectrum is observed to be in good agreement with the Standard Model expectation. In the context of the model proposed by Arkani-Hamed, Dimopoulos and Dvali, 95% confidence level lower limits of between 2.52 and 3.92 TeV are set on the ultraviolet cutoff scale MS depending on the number of extra dimensions and the theoretical formalism used. In the context of the Randall-Sundrum model, a lower limit of 2.06 (1.00) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/(M) over bar (Pl) = 0.1(0.01). Combining with the ATLAS dilepton searches based on the 2011 data, the 95% confidence level lower limit on the Randall-Sundrum graviton mass is further tightened to 2.23 (1.03) TeV for k/(M) over bar (Pl) = 0.1(0.01).
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58.
  • Aad, G., et al. (författare)
  • Search for pair-produced massive coloured scalars in four-jet final states with the ATLAS detector in proton-proton collisions at root s=7 TeV
  • 2013
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer. - 1434-6044 .- 1434-6052. ; 73:1
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for pair-produced massive coloured scalar particles decaying to a four-jet final state is performed by the ATLAS experiment at the LHC in proton-proton collisions at root s = 7 TeV. The analysed data sample corresponds to an integrated luminosity of 4.6 fb(-1). No deviation from the Standard Model is observed in the invariant mass spectrum of the two-jet pairs. A limit on the scalar gluon pair production cross section of 70 pb (10 pb) is obtained at the 95 % confidence level for a scalar gluon mass of 150 GeV (350 GeV). Interpreting these results as mass limits on scalar gluons, masses ranging from 150 GeV to 287 GeV are excluded at the 95 % confidence level.
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59.
  • Aad, G., et al. (författare)
  • Search for resonances decaying into top-quark pairs using fully hadronic decays in pp collisions with ATLAS at root s=7 TeV
  • 2013
  • Ingår i: Journal of High Energy Physics. - : Springer. - 1029-8479 .- 1126-6708. ; :1
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for resonances produced in 7 TeV proton-proton collisions and decaying into top-quark pairs is described. In this Letter events where the top-quark decay produces two massive jets with large transverse momenta recorded with the ATLAS detector at the Large Hadron Collider are considered. Two techniques that rely on jet substructure are used to separate top-quark jets from those arising from light quarks and gluons. In addition, each massive jet is required to have evidence of an associated bottom-quark decay. The data are consistent with the Standard Model, and limits can be set on the production cross section times branching fraction of a Z' boson and a Kaluza-Klein gluon resonance. These limits exclude, at the 95% credibility level, Z' bosons with masses 0.70-1.00 TeV as well as 1.28-1.32 TeV and Kaluza-Klein gluons with masses 0.70-1.62 TeV.
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60.
  • Aad, G., et al. (författare)
  • Search for resonant diboson production in the WW/WZ -> lvjj decay channels with the ATLAS detector at root s=7 TeV
  • 2013
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - : American Physical Society. - 1550-2368 .- 1550-7998. ; 87:11
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for resonant diboson production using a data sample corresponding to 4.7 fb(-1) of integrated luminosity collected by the ATLAS experiment at the Large Hadron Collider in pp collisions at root s = 7 TeV is presented. The search for a narrow resonance in the WW or WZ mass distribution is conducted in a final state with an electron or a muon, missing transverse momentum, and at least two jets. No significant excess is observed and limits are set using three benchmark models: WW resonance masses below 940 and 710 GeV are excluded at 95% confidence level for spin-2 Randall-Sundrum and bulk Randall-Sundrum gravitons, respectively; WZ resonance masses below 950 GeV are excluded at 95% confidence level for a spin-1 extended gauge model W' boson.
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  • Resultat 51-60 av 75
  • Föregående 1...2345[6]78Nästa

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