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@PHDTHESIS{Bessner:391008,
      author       = {Bessner, Martin},
      othercontributors = {Tackmann, Kerstin and Schleper, Peter},
      title        = {{M}easurement of differential di-photon plus jet cross
                      sections using the {ATLAS} detector},
      school       = {Universität Hamburg},
      type         = {Dissertation},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron},
      reportid     = {PUBDB-2017-10063, DESY-THESIS-2017-037},
      series       = {DESY-THESIS},
      pages        = {157},
      year         = {2017},
      note         = {Dissertation, Universität Hamburg, 2017},
      abstract     = {A good understanding of the strong interaction is crucial
                      for every experiment at a hadron collider. Events with
                      photons provide a direct access to study processes of the
                      strong interaction. This thesis presents the measurement of
                      differential cross sections of events with two photons as a
                      function of the number of hadronic jets. Photons are
                      required to be isolated from hadronic activity in the event.
                      Collision data is used corresponding to an integrated
                      luminosity of 20.3 fb$^{−1}$ at a proton-proton collision
                      energy of $\sqrt s$ = 8 TeV collected by the ATLAS detector
                      at the Large Hadron Collider (LHC) in 2012.The dominant
                      background contribution comes from hadronic jets which are
                      identified as photons, occurring mainly when a $π^0$
                      carries most of the jet energy. Two methods to remove this
                      contribution are presented. A smaller background
                      contribution arising from electrons misidentified as photons
                      is removed as well. The measured event yields are corrected
                      for detector inefficiencies and resolution effects. An
                      unfolding method based on singular value decomposition of
                      the resolution matrix is extended to two-dimensional
                      distributions and applied to the reconstructed
                      distributions. All systematic uncertainties are evaluated,
                      the dominant uncertainties arise from the jet background
                      subtraction and the uncertainty in the jet energy scale.16
                      observables are studied to explore the photon and jet
                      kinematics. Double differential cross sections are shown as
                      function of those observables and the number of jets, both
                      inclusively (≥ n jets) and exclusively (= n jets). The
                      results are compared to theoretical predictions from Sherpa,
                      Pythia and GoSam.},
      cin          = {ATLAS},
      cid          = {I:(DE-H253)ATLAS-20120731},
      pnm          = {611 - Fundamental Particles and Forces (POF3-611)},
      pid          = {G:(DE-HGF)POF3-611},
      experiment   = {EXP:(DE-H253)LHC-Exp-ATLAS-20150101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)29 / PUB:(DE-HGF)11},
      doi          = {10.3204/PUBDB-2017-10063},
      url          = {https://bib-pubdb1.desy.de/record/391008},
}