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Lorenz, Jeanette (2014): Search for strongly interacting supersymmetric particles decaying to final states with an isolated lepton with the ATLAS detector at the LHC. Dissertation, LMU München: Fakultät für Physik



Two analyses searching for squarks and gluinos which decay into final states with multiple jets, an isolated electron or muon and a large missing transverse energy are presented. Both rely on data taken by the ATLAS detector in pp collisions at a center-of-mass energy of 8 TeV at the LHC during 2012. The first analysis uses a subset of 5.8 fb-1 of this dataset, the other analysis uses the full statistics of 20.3 fb-1. Both analysis share the same methods regarding the triggers and the background estimation techniques. The two dominant backgrounds are ttbar and W+jets production. The ttbar and the W+jets backgrounds are estimated in a semi-data-driven method. The minor QCD multi-jet background is estimated in an entirely data-driven method. The final background estimates in the analyses are derived in a profile-log-likelihood fit. None of the analyses sees an excess beyond Standard Model expectations. The analysis of the partial dataset derives limits in a MSUGRA/CMSSM model with parameters A_0=0, tan(beta) = 10 and mu > 0 and excludes squarks and gluinos with masses below 1.2 TeV for equal squark and gluino masses. The analysis of the full dataset derives limits in simplified models and in a MSUGRA/CMSSM model with parameters A_0=-2 m_0, tan(beta) = 30 and mu > 0. Gluinos (squarks) with masses below 1.2 TeV (750 GeV) can be excluded for vanishing LSP masses in simplified models. Gluino masses below 1.2 TeV can be excluded for every m_0 value in the MSUGRA/CMSSM model.