@article{OPUS4-12956,
  title     = {Search for light scalar top-quark pair production in final states with two leptons with the ATLAS detector in √s=7 TeV proton-proton collisions},
  series = {The European Physical Journal C},
  volume    = {72},
  journal   = {The European Physical Journal C},
  number    = {2237},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-012-2237-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129561},
  year      = {2012},
  abstract  = {A search is presented for the pair production of light scalar top quarks in √s=7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. This analysis uses the full data sample collected during 2011 running that corresponds to a total integrated luminosity of 4.7 fb\(^{-1}\). Light scalar top quarks are searched for in events with two opposite-sign leptons (e, μ), large missing transverse momentum and at least one jet in the final state. No excess over Standard Model expectations is found, and the results are interpreted under the assumption that the light scalar top decays to a b-quark in addition to an on-shell chargino whose decay occurs through a virtual W boson. If the chargino mass is 106 GeV, light scalar top-quark masses up to 130 GeV are excluded for neutralino masses below 70 GeV.},
  language  = {en}
}
@article{OPUS4-12893,
  title     = {Measurement of \(t\overline t\) production with a veto on additional central jet activity in pp collisions at √s=7 TeV using the ATLAS detector},
  series = {European Physical Journal C},
  volume    = {72},
  journal   = {European Physical Journal C},
  number    = {2043},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-012-2043-9},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128931},
  year      = {2012},
  abstract  = {A measurement of the jet activity in \(t\overline t\) 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 \(t\overline t\) 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.},
  language  = {en}
}
@article{OPUS4-12890,
  title     = {Measurement of the charge asymmetry in top quark pair production in pp collisions at √s=7 TeV using the ATLAS detector},
  series = {The European Physical Journal C},
  volume    = {72},
  journal   = {The European Physical Journal C},
  number    = {2039},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-012-2039-5},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128904},
  year      = {2012},
  abstract  = {A measurement of the top-antitop production charge asymmetry A C is presented using data corresponding to an integrated luminosity of 1.04 fb\(^{-1}\) of pp collisions at √s=7 TeV collected by the ATLAS detector at the LHC. Events are selected with a single lepton (electron or muon), missing transverse momentum and at least four jets of which at least one jet is identified as coming from a b-quark. A kinematic fit is used to reconstruct the t\(\overline t\) event topology. After background subtraction, a Bayesian unfolding procedure is performed to correct for acceptance and detector effects. The measured value of A\(_C\) is AC=-0.019±0.028 (stat.)±0.024 (syst.), consistent with the prediction from the MC@NLO Monte Carlo generator of A\(_C\) =0.006±0.002. Measurements of A\(_C\) in two ranges of invariant mass of the top-antitop pair are also shown.},
  language  = {en}
}
@article{OPUS4-12889,
  title     = {Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 7 TeV proton-proton collision data with the},
  series = {The European Physical Journal C},
  volume    = {72},
  journal   = {The European Physical Journal C},
  number    = {2215},
  organization    = {ATLAS Collaboration},
  doi       = {dx.doi.org/10.1140/epjc/s10052-012-2215-7},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128891},
  year      = {2012},
  abstract  = {A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, and at least one hadronically decaying τ lepton, with zero or one additional light lepton (e/μ), has been performed using 4.7 fb\(^{-1}\) of proton-proton collision data at \(\sqrt s\)=7TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95 \% confidence level visible cross-section upper limit for new phenomena is set. In the framework of gauge-mediated SUSY-breaking models, lower limits on the mass scale Λ are set at 54 TeV in the regions where the \(\tilde τ_1\) is the next-to-lightest SUSY particle (tanβ>20). These limits provide the most stringent tests to date of GMSB models in a large part of the parameter space considered.},
  language  = {en}
}