@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{OPUS4-12955,
  title     = {A search for \(t\overline t\) resonances in lepton+jets events with highly boosted top quarks collected in pp collisions at √s=7 TeV with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {09},
  journal   = {Journal of High Energy Physics},
  number    = {41},
  organization    = {ATLAS Collaboration},
  doi       = {10.1007/JHEP09(2012)041},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129555},
  year      = {2012},
  abstract  = {A search for resonant production of high-mass top-quark pairs is performed on 2.05 fb\(^{-1}\) of proton-proton collisions at √s=7 TeV collected in 2011 with the ATLAS experiment at the Large Hadron Collider. This analysis of the lepton+jets final state is specifically designed for the particular topology that arises from the decay of highly boosted top quarks. The observed \(t\overline t\) invariant mass spectrum is found to be compatible with the Standard Model prediction and 95\% credibility level upper limits are derived on the \(t\overline t\) production rate through new massive states. An upper limit of 0.7 pb is set on the production cross section times branching fraction of a narrow 1 TeV resonance. A Kaluza-Klein gluon with a mass smaller than 1.5 TeV is excluded.},
  language  = {en}
}
@article{OPUS4-12954,
  title     = {Search for doubly charged Higgs bosons in like-sign dilepton final states at √s=7 TeV with the ATLAS detector},
  series = {The European Physical Journal C},
  volume    = {72},
  journal   = {The European Physical Journal C},
  number    = {2244},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-012-2244-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129540},
  year      = {2012},
  abstract  = {A search for doubly charged Higgs bosons decaying to pairs of electrons and/or muons is presented. The search is performed using a data sample corresponding to an integrated luminosity of 4.7 fb\(^{-1}\) of pp collisions at √s = 7 TeV collected by the ATLAS detector at the LHC. Pairs of prompt, isolated, high-p\(_T\) leptons with the same electric charge (\(e^±e^±, e^±μ^±, μ^±μ^±\)) are selected, and their invariant mass distribution is searched for a narrow resonance. No significant excess over Standard Model background expectations is observed, and limits are placed on the cross section times branching ratio for pair production of doubly charged Higgs bosons. The masses of doubly charged Higgs bosons are constrained depending on the branching ratio into these leptonic final states. Assuming pair production, coupling to left-handed fermions, and a branching ratio of 100 \% for each final state, masses below 409 GeV, 375 GeV, and 398 GeV are excluded for \(e^±e^±, e^±μ^±\), and \(μ^±μ^±\), respectively.},
  language  = {en}
}
@article{OPUS4-12917,
  title     = {Search for R-parity-violating supersymmetry in events with four or more leptons in √s=7 TeV pp collisions with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {12},
  journal   = {Journal of High Energy Physics},
  number    = {124},
  organization    = {ATLAS Collaboration},
  doi       = {10.1007/JHEP12(2012)124},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129179},
  year      = {2012},
  abstract  = {A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb\(^{-1}\) of √s=7 TeV proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires moderate values of missing transverse momentum and another that requires large effective mass. The results are interpreted in a simplified model of R-parity-violating supersymmetry in which a 95\% CL exclusion region is set for charged wino masses up to 540 GeV. In an R-parity-violating MSUGRA/CMSSM model, values of m 1/2 up to 820 GeV are excluded for 10 < tan β < 40.},
  language  = {en}
}
@article{OPUS4-12916,
  title     = {Search for charged Higgs bosons decaying via H\(^±\) → τν in \(t\overline t\) events using pp collision data at √s=7 TeV with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {06},
  journal   = {Journal of High Energy Physics},
  number    = {39},
  organization    = {ATLAS Collaboration},
  doi       = {10.1007/JHEP06(2012)039},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129163},
  year      = {2012},
  abstract  = {The results of a search for charged Higgs bosons are presented. The analysis is based on 4.6fb\(^{-1}\) of proton-proton collision data at √s=7TeV collected by the ATLAS experiment at the Large Hadron Collider, using top quark pair events with a τ lepton in the final state. The data are consistent with the expected background from Standard Model processes. Assuming that the branching ratio of the charged Higgs boson to a τ lepton and a neutrino is 100 \%, this leads to upper limits on the branching ratio of top quark decays to a b quark and a charged Higgs boson between 5\% and 1\% for charged Higgs boson masses ranging from 90 GeV to 160 GeV, respectively. In the context of the m\(^{max}_h\) scenario of the MSSM, tan β above 12-26, as well as between 1 and 2-6, can be excluded for charged Higgs boson masses between 90 GeV and 150 GeV.},
  language  = {en}
}
@article{OPUS4-12897,
  title     = {Jet mass and substructure of inclusive jets in √s=7 TeV pp collisions with the ATLAS experiment},
  series = {Journal of High Energy Physics},
  volume    = {05},
  journal   = {Journal of High Energy Physics},
  number    = {128},
  organization    = {ATLAS Collaboration},
  doi       = {10.1007/JHEP05(2012)128},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128970},
  year      = {2012},
  abstract  = {Recent studies have highlighted the potential of jet substructure techniques to identify the hadronic decays of boosted heavy particles. These studies all rely upon the assumption that the internal substructure of jets generated by QCD radiation is well understood. In this article, this assumption is tested on an inclusive sample of jets recorded with the ATLAS detector in 2010, which corresponds to 35 pb\(^{-1}\) of pp collisions delivered by the LHC at √s=7TeV. In a subsample of events with single pp collisions, measurements corrected for detector efficiency and resolution are presented with full systematic uncertainties. Jet invariant mass, k\(_t\) splitting scales and N-subjettiness variables are presented for anti-k\(_t\) R = 1.0 jets and Cambridge-Aachen R = 1.2 jets. Jet invariant-mass spectra for Cambridge-Aachen R = 1.2 jets after a splitting and filtering procedure are also presented. Leading-order parton-shower Monte Carlo predictions for these variables are found to be broadly in agreement with data. The dependence of mean jet mass on additional pp interactions is also explored.},
  language  = {en}
}
@article{OPUS4-12896,
  title     = {Search for same-sign top-quark production and fourth-generation down-type quarks in pp collisions at √s=7 TeV with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {04},
  journal   = {Journal of High Energy Physics},
  number    = {69},
  organization    = {ATLAS Collaboration},
  doi       = {10.1007/JHEP04(2012)069},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128960},
  year      = {2012},
  abstract  = {A search is presented for same-sign top-quark production and down-type heavy quarks of charge -1/3 in events with two isolated leptons (e or μ) that have the same electric charge, at least two jets and large missing transverse momentum. The data are selected from pp collisions at √s=7TeV recorded by the ATLAS detector and correspond to an integrated luminosity of 1.04 fb\(^{-1}\). The observed data are consistent with expectations from Standard Model processes. Upper limits are set at 95 \% confidence level on the cross section of new sources of same-sign top-quark pair production of 1.4-2.0 pb depending on the assumed mediator mass. Upper limits are also set on the pair-production cross-section for new heavy down-type quarks; a lower limit of 450 GeV is set at 95 \% confidence level on the mass of heavy down-type quarks under the assumption that they decay 100 \% of the time to W t.},
  language  = {en}
}
@article{OPUS4-12895,
  title     = {Search for second generation scalar leptoquarks in pp collisions at √s=7 TeV with the ATLAS detector},
  series = {The European Physical Journal C},
  volume    = {72},
  journal   = {The European Physical Journal C},
  number    = {2151},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-012-2151-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128957},
  year      = {2012},
  abstract  = {The results of a search for the production of second generation scalar leptoquarks are presented for final states consisting of either two muons and at least two jets or a muon plus missing transverse momentum and at least two jets. A total of 1.03 fb\(^{-1}\) integrated luminosity of proton-proton collision data produced by the Large Hadron Collider at s√=7 TeV and recorded by the ATLAS detector is used for the search. The event yields in the signal regions are found to be consistent with the Standard Model background expectations. The production of second generation leptoquarks is excluded for a leptoquark mass m\(_{LQ}\)<594 (685) GeV at 95 \% confidence level, for a branching ratio of 0.5 (1.0) for leptoquark decay to a muon and a quark.},
  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{OPUS4-12892,
  title     = {Measurement of the cross section for top-quark pair production in pp collisions at √s=7TeV with the ATLAS detector using final states with two high-p\(_T\) leptons},
  series = {Journal of High Energy Physics},
  volume    = {5},
  journal   = {Journal of High Energy Physics},
  number    = {59},
  organization    = {ATLAS Collaboration},
  doi       = {10.1007/JHEP05(2012)059},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128924},
  year      = {2012},
  abstract  = {A measurement is reported of the production cross section of top-quark pairs (\(t\overline t\)) in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. Candidate events have a signature consistent with containing two isolated leptons, large missing transverse momentum, and at least two jets. Using a data sample corresponding to an integrated luminosity of 0.70 fb\(^{-1}\), a \(t\overline t\) production cross section σ\(_{t\overline t}\)=176±5(stat.)\(^{+14}_{-11}\)(syst.)±8(lum.) pb is measured for an assumed top-quark mass of m\(_t\)  = 172.5 GeV. This measurement is in good agreement with Standard Model predictions.},
  language  = {en}
}