Measurement of the top quark-pair production cross section with ATLAS in pp collisions at TeV

A measurement of the production cross-section for top quark pairs () in pp collisions at is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron e or muon μ ) with large missing transverse energy and at least four jets, and dilepton (ee , μμ or eμ ) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb−1 , 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non- Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.9 events and 2.5±0.6 events, respectively. The kinematic properties of the selected events are consistent with SM production. The inclusive top quark pair production cross-section is measured to be The measurement agrees with perturbative QCD calculations.