@article{OPUS4-17256,
  title     = {Search for top quark decays \(t → qH\), with \(H → γγ\), in \(\sqrt{s} = 13\) TeV \(pp\) collisions using the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {2017},
  journal   = {Journal of High Energy Physics},
  number    = {10},
  organization    = {The ATLAS Collaboration},
  doi       = {https://doi.org/10.1007/JHEP10(2017)129},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172568},
  year      = {2017},
  abstract  = {This article presents a search for flavour-changing neutral currents in the decay of a top quark into an up-type (\({q = c, u}\)) quark and a Higgs boson, where the Higgs boson decays into two photons. The proton-proton collision data set analysed amounts to 36.1 fb\(^{-1}\) at \(\sqrt{s} = 13\) TeV collected by the ATLAS experiment at the LHC. Top quark pair events are searched for, where one top quark decays into \(qH\) and the other decays into \(bW\). Both the hadronic and leptonic decay modes of the \(W\) boson are used. No significant excess is observed and an upper limit is set on the \({t → cH}\) branching ratio of 2.2 × 10\(^{-3}\) at the 95\% confidence level, while the expected limit in the absence of signal is 1.6 × 10\(^{-3}\). The corresponding limit on the \(tcH\) coupling is 0.090 at the 95\% confidence level. The observed upper limit on the \({t → uH}\) branching ratio is 2.4 × 10\(^{-3}\).},
  language  = {en}
}
@article{OPUS4-17232,
  title     = {Search for supersymmetry in events with \(b\)-tagged jets and missing transverse momentum in \(pp\) collisions at \(\sqrt{s}\) = 13 TeV with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {2017},
  journal   = {Journal of High Energy Physics},
  number    = {195},
  organization    = {The ATLAS Collaboration},
  doi       = {10.1007/JHEP11(2017)195},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172320},
  year      = {2017},
  abstract  = {A search for the supersymmetric partners of the Standard Model bottom and top quarks is presented. The search uses 36.1 fb\(^{-1}\) of \(pp\) collision data at \(\sqrt{s}\) = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Direct production of pairs of bottom and top squarks (\(\overline{b}_1\) and \(\overline{t}_1\)) is searched for in final states with \(b\)-tagged jets and missing transverse momentum. Distinctive selections are defined with either no charged leptons (electrons or muons) in the final state, or one charged lepton. The zero-lepton selection targets models in which the \(\overline{b}_1\) is the lightest squark and decays via \(\overline{b}_1\) → \(b\overline{χ}^0_1\), where \(\overline{χ}^0_1\) is the lightest neutralino. The one-lepton final state targets models where bottom or top squarks are produced and can decay into multiple channels, \(\overline{b}_1\) → \(b\overline{χ}^0_1\) and \(\overline{b}_1\) → \(t\overline{χ}^±_1\), or \(\overline{t}_1\) → \(t\overline{χ}^0_1\) and \(\overline{t}_1\) → \(b\overline{χ}^±_1\), where \(\overline{χ}^±_1\) is the lightest chargino and the mass difference \(m_{\overline{χ}^±_1}\) - \(m_{\overline{χ}^0_1}\) is set to 1 GeV. No excess above the expected Standard Model background is observed. Exclusion limits at 95\% confidence level on the mass of third-generation squarks are derived in various supersymmetry-inspired simplified models.},
  language  = {en}
}
@article{OPUS4-17280,
  title     = {Search for new phenomena in a lepton plus high jet multiplicity final state with the ATLAS experiment using \(\sqrt{s}=13\) TeV proton-proton collision data},
  series = {Journal of High Energy Physics},
  volume    = {2017},
  journal   = {Journal of High Energy Physics},
  number    = {09},
  organization    = {The ATLAS Collaboration},
  doi       = {https://doi.org/10.1007/JHEP09(2017)088},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172802},
  year      = {2017},
  abstract  = {A search for new phenomena in final states characterized by high jet multiplicity, an isolated lepton (electron or muon) and either zero or at least three \(b\)-tagged jets is presented. The search uses 36.1 fb\(^{-1}\) of \(\sqrt{s}=13\) TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider in 2015 and 2016. The dominant sources of background are estimated using parameterized extrapolations, based on observables at medium jet multiplicity, to predict the \(b\)-tagged jet multiplicity distribution at the higher jet multiplicities used in the search. No significant excess over the Standard Model expectation is observed and 95\% confidence-level limits are extracted constraining four simplified models of \(R\)-parity-violating supersymmetry that feature either gluino or top-squark pair production. The exclusion limits reach as high as 2.1 TeV in gluino mass and 1.2 TeV in top-squark mass in the models considered. In addition, an upper limit is set on the cross-section for Standard Model \(t\overline{t}t\overline{t}\) production of 60 fb (6.5 × the Standard Model prediction) at 95\% confidence level. Finally, model-independent limits are set on the contribution from new phenomena to the signal-region yields.},
  language  = {en}
}
@article{OPUS4-17216,
  title     = {Search for a scalar partner of the top quark in the jets plus missing transverse momentum final state at \(\sqrt{s}\) = 13 TeV with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {12},
  journal   = {Journal of High Energy Physics},
  organization    = {The ATLAS Collaboration},
  doi       = {10.1007/JHEP12(2017)085},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172161},
  year      = {2017},
  abstract  = {A search for pair production of a scalar partner of the top quark in events with four or more jets plus missing transverse momentum is presented. An analysis of 36.1 fb\(^{-1}\) of \(\sqrt{s}\) = 13 TeV proton-proton collisions collected using the ATLAS detector at the LHC yields no significant excess over the expected Standard Model background. To interpret the results a simplified supersymmetric model is used where the top squark is assumed to decay via \(\tilde{t}_1\) → \(t^{(∗)}\)\(\tilde{χ}^0_1\) and \(\tilde{t}_1\) → \(b\tilde{χ}^±_1\) → \({bW}^{(∗)}\tilde{χ}^0_1\), where \(\tilde{χ}^0_1\) (\(\tilde{χ}^±_1\)) denotes the lightest neutralino (chargino). Exclusion limits are placed in terms of the top-squark and neutralino masses. Assuming a branching ratio of 100\% to \(t\tilde{χ}^0_1\), top-squark masses in the range 450-1000 GeV are excluded for \(\tilde{χ}^0_1\) masses below 160 GeV. In the case where \(m_{\tilde{t}_1}\) ∼ \(m_t\) + \(m_{\tilde{χ}^0_1}\), top-squark masses in the range 235-590 GeV are excluded.},
  language  = {en}
}