@article{OPUS4-17231,
  title     = {Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the \(t\)-channel at \(\sqrt{s}\) = 8 TeV with the ATLAS detector},
  series = {Journal or High Energy Physics},
  volume    = {2017},
  journal   = {Journal or High Energy Physics},
  number    = {17},
  organization    = {The ATLAS Collaboration},
  doi       = {10.1007/JHEP12(2017)017},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172310},
  year      = {2017},
  abstract  = {The electroweak production and subsequent decay of single top quarks in the \(t\)-channel is determined by the properties of the \({Wtb}\) vertex, which can be described by the complex parameters of an effective Lagrangian. An analysis of a triple-differential decay rate in \(t\)-channel production is used to simultaneously determine five generalised helicity fractions and phases, as well as the polarisation of the produced top quark. The complex parameters are then constrained. This analysis is based on 20.2 fb\(^{-1}\) of proton-proton collision data at a centre-of-mass energy of 8 TeV collected with the ATLAS detector at the LHC. The fraction of decays containing transversely polarised \(W\) bosons is measured to be \(f_1\) = 0.30 ± 0.05. The phase between amplitudes for transversely and longitudinally polarised \(W\) bosons recoiling against left-handed \(b\)-quarks is measured to be \(\delta\)_ = 0.002\(\pi^{+0.016\pi}_{+0.017\pi}\), giving no indication of CP violation. The fractions of longitudinal or transverse \(W\) bosons accompanied by right-handed \(b\)-quarks are also constrained. Based on these measurements, limits are placed at 95\% CL on the ratio of the complex coupling parameters Re [\({g_R/V_L}\) \(\in\) [-0.12, 0.17] and Im [\({g_R/V_L}\) \(\in\) [-0.07, 0.06]. Constraints are also placed on the ratios |\({V_R}/{V_L}\)| and |\({g_L}/{V_L}\)|. In addition, the polarisation of single top quarks in the \(t\)-channel is constrained to be \(P\) > 0.72 (95\% CL). None of the above measurements make assumptions about the value of any of the other parameters or couplings and all of them are in agreement with the Standard Model.},
  language  = {en}
}
@article{OPUS4-17322,
  title     = {Studies of \(Zγ\) production in association with a high-mass dijet system in \(pp\) collisions at \(\sqrt{s}\) = 8 TeV with the ATLAS detector},
  series = {Journal of High Energy Physics},
  volume    = {2017},
  journal   = {Journal of High Energy Physics},
  number    = {07},
  organization    = {The ATLAS Collaboration},
  doi       = {https://doi.org/10.1007/JHEP07(2017)107},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173229},
  year      = {2017},
  abstract  = {The production of a \(Z\) boson and a photon in association with a high-mass dijet system is studied using 20.2 fb\(^{-1}\) of proton-proton collision data at a centre-of-mass energy of \(\sqrt{s}\) = 8 TeV recorded with the ATLAS detector in 2012 at the Large Hadron Collider. Final states with a photon and a Z boson decaying into a pair of either electrons, muons, or neutrinos are analysed. Electroweak and total \(pp\) → \(Zγjj\) cross-sections are extracted in two fiducial regions with different sensitivities to electroweak production processes. Quartic couplings of vector bosons are studied in regions of phase space with an enhanced contribution from pure electroweak production, sensitive to vector-boson scattering processes \(V V → Zγ\). No deviations from Standard Model predictions are observed and constraints are placed on anomalous couplings parameterized by higher-dimensional operators using effective field theory.},
  language  = {en}
}