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Open Access Publications from the University of California

Scholarly Works (529 results)

  • Article
  • Peer Reviewed
UC Berkeley Previously Published Works (2012)
A search for a Standard Model Higgs boson decaying via H→ZZ→ℓ+ℓ−νν¯ where ℓ represents electrons or muons, is presented. It is based on proton-proton collision data at s=7 TeV, collected by the ATLAS experiment at the LHC during 2011 and corresponding to an integrated luminosity of 4.7 fb−1. The data agree with the expected Standard Model backgrounds. Upper limits on the Higgs boson production cross section are derived for Higgs boson masses between 200 GeV and 600 GeV and the production of a Standard Model Higgs boson with a mass in the range 319–558 GeV is excluded at the 95% confidence level.
    Cover page: Search for a standard model Higgs boson in the H→ZZ→ℓ+ℓ−νν¯ decay channel using 4.7 fb−1 of s=7 TeV data with the ATLAS detectorCreative Commons 'BY' version 4.0 license
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2012)
    This Letter describes the measurement of elliptic flow of charged particles in lead-lead collisions at sNN=2.76 TeV using the ATLAS detector at the Large Hadron Collider (LHC). The results are based on an integrated luminosity of approximately 7 μb-1. Elliptic flow is measured over a wide region in pseudorapidity, |η|<2.5, and over a broad range in transverse momentum, 0.5
      Cover page: Measurement of the pseudorapidity and transverse momentum dependence of the elliptic flow of charged particles in lead–lead collisions at sNN=2.76&nbsp;TeV with the ATLAS detectorCreative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2016)
      This paper presents studies of the performance of several jet-substructure techniques, which are used to identify hadronically decaying top quarks with high transverse momentum contained in large-radius jets. The efficiency of identifying top quarks is measured using a sample of top-quark pairs and the rate of wrongly identifying jets from other quarks or gluons as top quarks is measured using multijet events collected with the ATLAS experiment in 20.3 fb−1of 8 TeV proton-proton collisions at the Large Hadron Collider. Predictions from Monte Carlo simulations are found to provide an accurate description of the performance. The techniques are compared in terms of signal efficiency and background rejection using simulations, covering a larger range in jet transverse momenta than accessible in the dataset. Additionally, a novel technique is developed that is optimized to reconstruct top quarks in events with many jets.[Figure not available: see fulltext.]
        Cover page: Identification of high transverse momentum top quarks in pp collisions at s=8 TeV with the ATLAS detectorCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Santa Cruz Previously Published Works (2013)
        A search for new particles that decay into top quark pairs (tt) is performed with the ATLAS experiment at the LHC using an integrated luminosity of 4.7 fb–1of proton–proton (pp) collision data collected at a center-of-mass energy √s = 7 TeV. In the tt̄→ WbWb decay, the lepton plus jets final state is used, where one W boson decays leptonically and the other hadronically. The tt̄system is reconstructed using both small-radius and large-radius jets, the latter being supplemented by a jet substructure analysis. A search for local excesses in the number of data events compared to the Standard Model expectation in the tt̄invariant mass spectrum is performed. No evidence for a tt̄resonance is found and 95% credibility-level limits on the production rate are determined for massive states predicted in two benchmark models. The upper limits on the cross section times branching ratio of a narrow Z′ resonance range from 5.1 pb for a boson mass of 0.5 TeV to 0.03 pb for a mass of 3 TeV. A narrow leptophobic topcolor Z′ resonance with a mass below 1.74 TeV is excluded. Limits are also derived for a broad color-octet resonance with Γ/m = 15.3%. A Kaluza–Klein excitation of the gluon in a Randall–Sundrum model is excluded for masses below 2.07 TeV.
          Cover page: Search for tt¯ resonances in the lepton plus jets final state with ATLAS using 4.7 fb-1 of pp collisions at s=7 TeVCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed