A novel approach to precision measurements of the top quark-antiquark pair production cross section with the ATLAS experiment

This doctoral thesis presents three measurements of the top quark-antiquark pair production cross section in proton-proton collisions at a centre-of-mass energy of \mbox{$\sqrt{s} = 7$~TeV} recorded in 2010 and 2011 with the ATLAS Experiment at the Large Hadron Collider. Events are selected in the single lepton topology by requiring an electron or muon, large missing transverse momentum and at least three jets. While one analysis relies on kinematic information only to discriminate the $t\bar{t}$ signal from the background processes, the other two also make use of $b$-tagging information. With the help of multivariate methods the most precise measurements in this topology are obtained. This is for two of the measurements in particular possible due to the use of a profile likelihood method which is studied in detail. For the first time a fiducial inclusive cross section measurement for top quark events is performed allowing a measurement almost independent of theoretical uncertainties. All measurements are in agreement with theory predictions performed in perturbation theory at approximate NNLO.