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Open Access Publications from the University of California

Scholarly Works (157 results)

  • Article
LBL Publications (1987)
    Cover page: OPERATING RESULTS FOR THE BEAM PROFILE MONITOR SYSTEM CURRENTLY IN USE AT BEVALAC FACILITY
    • Article
    LBL Publications (1993)
      Cover page: Status Report on the Advanced Light Source Control System, 1993
      • Article
      LBL Publications (1991)
        Cover page: Status Report on the Advanced Light Source Control System, 1993
        • Article
        • Peer Reviewed
        UC Santa Cruz Previously Published Works (2012)
        A combined search for the Standard Model Higgs boson with the ATLAS experiment at the LHC using datasets corresponding to integrated luminosities from 1.04 fb-1 to 4.9 fb-1 of pp collisions collected at s=7TeV is presented. The Higgs boson mass ranges 112.9-115.5 GeV, 131-238 GeV and 251-466 GeV are excluded at the 95% confidence level (CL), while the range 124-519 GeV is expected to be excluded in the absence of a signal. An excess of events is observed around mH~126GeV with a local significance of 3.5 standard deviations (σ). The local significances of H→γγ, H→ZZ(z.ast;)→ℓ+ℓ-ℓ'+ℓ'- and H→WW(z.ast;)→ℓ+νℓ'-ν- the three most sensitive channels in this mass range, are 2.8σ, 2.1σ and 1.4σ, respectively. The global probability for the background to produce such a fluctuation anywhere in the explored Higgs boson mass range 110-600 GeV is estimated to be ~1.4% or, equivalently, 2.2σ. © 2012 CERN.
          Cover page: Combined search for the Standard Model Higgs boson using up to 4.9 fb−1 of pp collision data at s=7 TeV with the ATLAS detector at the LHCCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC Santa Cruz Previously Published Works (2012)
          A measurement of the jet activity in [Formula: see text] events produced in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb-1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. The [Formula: see text] events are selected in the dilepton decay channel with two identified b-jets from the top quark decays. Events are vetoed if they contain an additional jet with transverse momentum above a threshold in a central rapidity interval. The fraction of events surviving the jet veto is presented as a function of this threshold for four different central rapidity interval definitions. An alternate measurement is also performed, in which events are vetoed if the scalar transverse momentum sum of the additional jets in each rapidity interval is above a threshold. In both measurements, the data are corrected for detector effects and compared to the theoretical models implemented in MC@NLO, Powheg, Alpgen and Sherpa. The experimental uncertainties are often smaller than the spread of theoretical predictions, allowing deviations between data and theory to be observed in some regions of phase space.
            Cover page: Measurement of production with a veto on additional central jet activity in pp collisions at TeV using the ATLAS detectorCreative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC Santa Cruz Previously Published Works (2012)
            Pseudorapidity gap distributions in proton-proton collisions at √s = 7 TeV are studied using a minimum bias data sample with an integrated luminosity of 7.1 μb−1. Cross sections are measured differentially in terms of ΔηF, the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at η = ±4.9, in which no final state particles are produced above a transverse momentum threshold pcutT. The measurements span the region 0 < ΔηF < 8 for 200 MeV < pcutT < 800 MeV. At small ΔηF, the data test the reliability of hadronisation models in describing rapidity and transverse momentum fluctuations in final state particle production. The measurements at larger gap sizes are dominated by contributions from the single diffractive dissociation process (pp →Xp), enhanced by double dissociation (pp → XY) where the invariant mass of the lighter of the two dissociation systems satisfies MY < 7 GeV. The resulting cross section is dσ/dΔηF ≈1 mb for ΔηF > 3. The large rapidity gap data are used to constrain the value of the Pomeron intercept appropriate to triple Regge models of soft diffraction. The cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements.
              Cover page: Rapidity gap cross sections measured with the ATLAS detector in pp collisions atCreative Commons 'BY' version 4.0 license
              • Article
              • Peer Reviewed
              UC Irvine Previously Published Works (2011)
              A search for neutral Higgs bosons decaying to pairs of τ leptons with the ATLAS detector at the LHC is presented. The analysis is based on proton-proton collisions at a center-of-mass energy of 7 TeV, recorded in 2010 and corresponding to an integrated luminosity of 36 pb-1. After signal selection, 276 events are observed in this data sample. The observed number of events is consistent with the total expected background of 269±36 events. Exclusion limits at the 95% confidence level are derived for the production cross section of a generic Higgs boson φ as a function of the Higgs boson mass and for A/H/h production in the Minimal Supersymmetric Standard Model (MSSM) as a function of the parameters mA and tanβ. © 2011 CERN.
                Cover page: Search for neutral MSSM Higgs bosons decaying to τ+τ− pairs in proton–proton collisions at s=7 TeV with the ATLAS detectorCreative Commons 'BY' version 4.0 license
                • Article
                • Peer Reviewed
                UC Irvine Previously Published Works (2012)
                We present an update of a search for supersymmetry in final states containing jets, missing transverse momentum, and one isolated electron or muon, using 1.04fb -1 of proton-proton collision data at √s=7TeV recorded by the ATLAS experiment at the LHC in the first half of 2011. The analysis is carried out in four distinct signal regions with either three or four jets and variations on the (missing) transverse momentum cuts, resulting in optimized limits for various supersymmetry models. No excess above the standard model background expectation is observed. Limits are set on the visible cross section of new physics within the kinematic requirements of the search. The results are interpreted as limits on the parameters of the minimal supergravity framework, limits on cross sections of simplified models with specific squark and gluino decay modes, and limits on parameters of a model with bilinear R-parity violation. © 2012 CERN.
                  Cover page: Search for supersymmetry in final states with jets, missing transverse momentum and one isolated lepton in s=7 TeV pp collisions using 1 fb-1 of ATLAS dataCreative Commons 'BY' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2012)
                  The ATLAS detector is used to search for excited leptons in the electromagnetic radiative decay channel *→γ. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 2.05fb-1. No evidence for excited leptons is found, and limits are set on the compositeness scale Λ as a function of the excited lepton mass m *. In the special case where Λ=m *, excited electron and muon masses below 1.87 TeV and 1.75 TeV are excluded at 95% C.L., respectively. © 2012 CERN.
                    Cover page: Search for excited leptons in proton-proton collisions at s=7 TeV with the ATLAS detectorCreative Commons 'BY' version 4.0 license
                    • Article
                    • Peer Reviewed
                    UC Santa Cruz Previously Published Works (2012)
                    Results of three searches are presented for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons, e or μ. The analysis uses a data sample collected during the first half of 2011 that corresponds to a total integrated luminosity of 1fb-1 of s=7TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are separately studied, with no deviations from the Standard Model expectation observed. Additionally, in opposite-sign events, a search is made for an excess of same-flavour over different-flavour lepton pairs. Effective production cross sections in excess of 9.9 fb for opposite-sign events containing supersymmetric particles with missing transverse momentum greater than 250 GeV are excluded at 95% CL. For same-sign events containing supersymmetric particles with missing transverse momentum greater than 100 GeV, effective production cross sections in excess of 14.8 fb are excluded at 95% CL. The latter limit is interpreted in a simplified electroweak gaugino production model excluding chargino masses up to 200 GeV, under the assumption that slepton decay is dominant. © 2012 CERN.
                      Cover page: Searches for supersymmetry with the ATLAS detector using final states with two leptons and missing transverse momentum in s=7&nbsp;TeV proton–proton collisionsCreative Commons 'BY' version 4.0 license
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