@article{OPUS4-17369,
  title     = {A measurement of the calorimeter response to single hadrons and determination of the jet energy scale uncertainty using LHC Run-1 \(pp\)-collision data with the ATLAS detector},
  series = {European Physical Journal C},
  volume    = {77},
  journal   = {European Physical Journal C},
  number    = {26},
  organization    = {The ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-016-4580-0},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173690},
  year      = {2017},
  abstract  = {A measurement of the calorimeter response to isolated charged hadrons in the ATLAS detector at the LHC is presented. This measurement is performed with 3.2 nb\(^{-1}\) of proton-proton collision data at \(\sqrt{s}\) = 7 TeV from 2010 and 0.1 nb\(^{-1}\) of data at \(\sqrt{s}\) = 8 TeV from 2012. A number of aspects of the calorimeter response to isolated hadrons are explored. After accounting for energy deposited by neutral particles, there is a 5\% discrepancy in the modelling, using various sets of GEANT4 hadronic physics models, of the calorimeter response to isolated charged hadrons in the central calorimeter region. The description of the response to anti-protons at low momenta is found to be improved with respect to previous analyses. The electromagnetic and hadronic calorimeters are also examined separately, and the detector simulation is found to describe the response in the hadronic calorimeter well. The jet energy scale uncertainty and correlations in scale between jets of different momenta and pseudorapidity are derived based on these studies. The uncertainty is 2-5\% for jets with transverse momenta above 2 TeV, where this method provides the jet energy scale uncertainty for ATLAS.},
  language  = {en}
}
@article{OPUS4-14423,
  title     = {Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector},
  series = {Physics Letters B},
  volume    = {749},
  journal   = {Physics Letters B},
  organization    = {ATLAS Collaboration},
  doi       = {10.1016/j.physletb.2015.07.079},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144231},
  pages     = {519-541},
  year      = {2015},
  abstract  = {A search for the associated production of the Higgs boson with a top quark pair is performed in multilepton final states using 20.3 fb\(^{-1}\) of proton-proton collision data recorded by the ATLAS experiment at \(\sqrt {s}\)=8 TeV at the Large Hadron Collider. Five final states, targeting the decays H→WW\(^{*}\), ττ, and ZZ\(^{*}\), are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons (e or μ) without a hadronically decaying τ lepton; three light leptons; two same-charge light leptons with a hadronically decaying τ lepton; four light leptons; and one light lepton and two hadronically decaying τ leptons. No significant excess of events is observed above the background expectation. The best fit for the t\(\overline{t}\)H production cross section, assuming a Higgs boson mass of 125 GeV, is 2.1\(^{+1.4}_{-1.2}\) times the SM expectation, and the observed (expected) upper limit at the 95\% confidence level is 4.7 (2.4) times the SM rate. The p-value for compatibility with the background-only hypothesis is 1.8σ; the expectation in the presence of a Standard Model signal is 0.9σ.},
  language  = {en}
}
@article{OPUS4-14424,
  title     = {Measurement of exclusive γγ→ℓ\(^{+}\)ℓ\(^{-}\) production in proton-proton collisions at \(\sqrt {s}\)=7 TeV with the ATLAS detector},
  series = {Physics Letters B},
  volume    = {749},
  journal   = {Physics Letters B},
  organization    = {ATLAS Collaboration},
  doi       = {10.1016/j.physletb.2015.07.069},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144247},
  pages     = {242-261},
  year      = {2015},
  abstract  = {This Letter reports a measurement of the exclusive γγ→ℓ\(^{+}\)ℓ\(^{-}\) (ℓ=e, μℓ=e, μ) cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of 4.6 fb\(^{-1}\). For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be \(^{excl.}_{γγ→e^{+}e^{-}}\)=0.428 ± 0.035 (stat.) ± 0.018 (syst.) pb for a phase-space region with invariant mass of the electron pairs greater than 24 GeV, in which both electrons have transverse momentum p\(_{T}\)>12 GeV and pseudorapidity |η|<2.4. For muon pairs with invariant mass greater than 20 GeV, muon transverse momentum p\(_{T}\)>10 GeV and pseudorapidity |η|<2.4, the cross-section is determined to be \(^{excl.}_{γγ→μ^{+}μ^{-}}\) =0.628 ± 0.032 (stat.) ± 0.021 (syst.) pb. When proton absorptive effects due to the finite size of the proton are taken into account in the theory calculation, the measured cross-sections are found to be consistent with the theory prediction.},
  language  = {en}
}
@article{OPUS4-14422,
  title     = {Measurement of colour flow with the jet pull angle in t\(\overline{t}\) events using the ATLAS detector at \(\sqrt {s}\)=8 TeV},
  series = {Physics Letters B},
  volume    = {750},
  journal   = {Physics Letters B},
  organization    = {ATLAS Collaboration},
  doi       = {10.1016/j.physletb.2015.09.051},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144229},
  pages     = {475-493},
  year      = {2015},
  abstract  = {The distribution and orientation of energy inside jets is predicted to be an experimental handle on colour connections between the hard-scatter quarks and gluons initiating the jets. This Letter presents a measurement of the distribution of one such variable, the jet pull angle. The pull angle is measured for jets produced in t\(\overline{t}\) events with one W boson decaying leptonically and the other decaying to jets using 20.3 fb\(^{-1}\) of data recorded with the ATLAS detector at a centre-of-mass energy of \(\sqrt {s}\)=8 TeV at the LHC. The jet pull angle distribution is corrected for detector resolution and acceptance effects and is compared to various models.},
  language  = {en}
}
@article{ChiesaGreinerSchoenherretal.2017,
  author    = {Chiesa, Mauro and Greiner, Nicolas and Sch{\"o}nherr, Marek and Tramontano, Francesco},
  title     = {Electroweak corrections to diphoton plus jets},
  series = {Journal of High Energy Physics},
  journal   = {Journal of High Energy Physics},
  number    = {10},
  doi       = {10.1007/JHEP10(2017)181},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173512},
  year      = {2017},
  abstract  = {We calculate the next-to-leading order electroweak corrections to the production of a photon pair in association with zero, one and two jets at the LHC. We use GoSam and Sherpa to obtain the results in a fully automated way. For a typical set of fiducial cuts the electroweak corrections lead to a modification of the total cross section of up to 3\%, depending on the jet multiplicity. We find substantial contributions in differential distributions, leading to tens of per cent corrections for phase space regions within the reach of the LHC. Furthermore we investigate the importance of photon induced processes as well as subleading contributions. Photon induced processes are found to be negligible, subleading contributions can have a sizeable impact however they can be removed by appropriate phase space cuts.},
  language  = {en}
}
@article{OPUS4-17371,
  title     = {Search for triboson \({W^\pm}{W^\pm}{W^\mp}\) production in \(pp\) collisions at \(\sqrt{s}\) = 8 TeV with the ATLAS detector},
  series = {European Physical Journal C},
  volume    = {77},
  journal   = {European Physical Journal C},
  number    = {141},
  organization    = {The ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-017-4692-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173710},
  year      = {2017},
  abstract  = {This paper reports a search for triboson \({W^\pm}{W^\pm}{W^\mp}\) production in two decay channels (\({W^\pm}{W^\pm}{W^\mp}\) → \({ℓ^\pm}{νℓ^\pm}{νℓ^\mp}{ν}\) and \({W^\pm}{W^\pm}{W^\mp}\) → \({ℓ^\pm}{νℓ^\pm}{νjj}\) with \(ℓ=e,μ\)) in proton-proton collision data corresponding to an integrated luminosity of 20.3 fb\(^{-1}\) at a centre-of-mass energy of 8 TeV with the ATLAS detector at the Large Hadron Collider. Events with exactly three charged leptons, or two leptons with the same electric charge in association with two jets, are selected. The total number of events observed in data is consistent with the Standard Model (SM) predictions. The observed 95\% confidence level upper limit on the SM \({W^\pm}{W^\pm}{W^\mp}\) production cross section is found to be 730 fb with an expected limit of 560 fb in the absence of SM \({W^\pm}{W^\pm}{W^\mp}\) production. Limits are also set on \(WWWW\) anomalous quartic gauge couplings.},
  language  = {en}
}
@article{OPUS4-17360,
  title     = {Measurements of charge and CP asymmetries in \(b\)-hadron decays using top-quark events collected by the ATLAS detector in \(pp\) collisions at \(\sqrt{s}\) = 8 TeV},
  series = {Journal of High Energy Physics},
  volume    = {2017},
  journal   = {Journal of High Energy Physics},
  number    = {02},
  organization    = {The ATLAS Collaboration},
  doi       = {10.1007/JHEP02(2017)071},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173603},
  year      = {2017},
  abstract  = {Same- and opposite-sign charge asymmetries are measured in lepton+jets \({t\overline{t}}\) events in which a \(b\)-hadron decays semileptonically to a soft muon, using data corresponding to an integrated luminosity of 20.3 fb\(^{-1}\) from proton-proton collisions at a centre-of-mass energy of \(\sqrt{s}\) = 8 TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. The charge asymmetries are based on the charge of the lepton from the top-quark decay and the charge of the soft muon from the semileptonic decay of a \(b\)-hadron and are measured in a fiducial region corresponding to the experimental acceptance. Four CP asymmetries (one mixing and three direct) are measured and are found to be compatible with zero and consistent with the Standard Model.},
  language  = {en}
}
@article{OPUS4-14985,
  title     = {Jet energy measurement and its systematic uncertainty in proton-proton collisions at \(\sqrt {s}\)=7 TeV with the ATLAS detector},
  series = {European Physical Journal C: Particles and Fields},
  volume    = {75},
  journal   = {European Physical Journal C: Particles and Fields},
  number    = {1},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-014-3190-y},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149854},
  pages     = {17},
  year      = {2015},
  abstract  = {The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton-proton collision data with a centre-of-mass energy of \(\sqrt {s}\)=7 TeV corresponding to an integrated luminosity of 4.7 fb\(^{-1}\). Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti-k\(_t\) algorithm with distance parameters R=0.4 or R=0.6, and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a Z boson, for 20≤p\(^{jet}_{T}\)<1000 GeV and pseudorapidities |η|<4.5. The effect of multiple proton-proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1 \% is found in the central calorimeter region (|η|<1.2) for jets with 55≤p\(^{jet}_{T}\)<500 GeV. For central jets at lower p\(_{T}\), the uncertainty is about 3 \%. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton-proton collisions and test-beam data, which also provide the estimate for p\(^{jet}_{T}\)>1 TeV. The calibration of forward jets is derived from dijet p\(_{T}\) balance measurements. The resulting uncertainty reaches its largest value of 6 \% for low-p\(_{T}\) jets at |η|=4.5. Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5-3 \%.},
  language  = {en}
}
@article{OPUS4-15009,
  title     = {Search for direct pair production of a chargino and a neutralino decaying to the 125 GeV Higgs boson in \(\sqrt {s}\) = 8 TeV pp collisions with the ATLAS detector},
  series = {European Physical Journal C: Particles and Fields},
  volume    = {75},
  journal   = {European Physical Journal C: Particles and Fields},
  number    = {5},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-015-3408-7},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150099},
  pages     = {208},
  year      = {2015},
  abstract  = {A search is presented for the direct pair production of a chargino and a neutralino pp → \(\tilde{χ}\)\(^{±}_{1}\)\(\tilde{χ}\)\(^{0}_{2}\), where the chargino decays to the lightest neutralino and the W boson, \(\tilde{χ}\)\(^{±}_{1}\)→\(\tilde{χ}\)\(^{0}_{1}\)(W\(^{±}\)→ℓ\(^{±}\)ν), while the neutralino decays to the lightest neutralino and the 125 GeV Higgs boson, \(\tilde{χ}\)\(^{0}_{2}\)→\(\tilde{χ}\)\(^{0}_{1}\)(h→bb/γγ/ℓ\(^{±}\)νqq). The final states considered for the search have large missing transverse momentum, an isolated electron or muon, and one of the following: either two jets identified as originating from bottom quarks, or two photons, or a second electron or muon with the same electric charge. The analysis is based on 20.3 fb\(^{-1}\) of \(\sqrt {s}\) = 8 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations, and limits are set in the context of a simplified supersymmetric model.},
  language  = {en}
}
@article{OPUS4-15019,
  title     = {Search for the Standard Model Higgs boson produced in association with top quarks and decaying into b\(\overline{b}\) in pp collisions at \(\sqrt {s}\) = 8 TeV with the ATLAS detector},
  series = {European Physical Journal C: Particles and Fields},
  volume    = {75},
  journal   = {European Physical Journal C: Particles and Fields},
  number    = {7},
  organization    = {ATLAS Collaboration},
  doi       = {10.1140/epjc/s10052-015-3543-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150197},
  pages     = {349},
  year      = {2015},
  abstract  = {A search for the Standard Model Higgs boson produced in association with a top-quark pair, t\(\overline{t}\)H, is presented. The analysis uses 20.3 fb\(^{-1}\) of pp collision data at \(\sqrt {s}\) = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H→b\(\overline{b}\) decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by t\(\overline{t}\)+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible t\(\overline{t}\)+b\(\overline{b}\) background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 \% confidence level. The ratio of the measured t\(\overline{t}\)H signal cross section to the Standard Model expectation is found to be μ = 1.5 ± 1.1 assuming a Higgs boson mass of 125 GeV.},
  language  = {en}
}