Brau, JamesSearcy, Jacob2013-07-112013-07-112013-07-11https://hdl.handle.net/1794/12944The measurement of the cross section of top quark pair production in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb-1 . Events with an isolated electron or muon and a tau lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b-quark. The measured cross section, σtt̄ = 178 ± 12 stat. ± 18 sys. ± 7 lumi. pb, is in good agreement with the Standard Model prediction.en-USAll Rights Reserved.Electronic Thesis or Dissertation