Measurement of the top quark-pair cross-section with ATLAS in pp collisions at sqrt(s) = 7 TeV in the single-lepton channel using b-tagging

A measurement of the production cross section for top-quark pairs in pp collisions at sqrt(s) = 7 TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in the single lepton (electron or muon) channel making use of the detector b-tagging capabilities. With a data sample of 35.3/pb the inclusive top quark production cross section is measured to be sigma_tt = 186 +-10 (stat.) +21-20 (syst.) +- 6 (lumi.) pb = 186 +24-23 pb. Cross-checks measurements are performed with kinematic fits of the reconstructed top mass and “cut and count” methods and are found to be in good agreement with this result. The measurement agrees with perturbative QCD calculations.