Top Quark Pair Production Cross-Section at ATLAS

Measurements of the top quark pair (tt) production cross-section in proton-proton collisions at √s = 7 TeV are presented using data recorded with the ATLAS detector at the Large Hadron Collider (LHC). The statistical combination of tt production cross-section (σtt) measurements is presented using the lepton+jets, dilepton and all-hadronic channel. A new measurement of σtt with a hadronically decaying tau lepton and jets is also shown, together with an updated measurement in the all-hadronic channel. Finally a measurement of the jet activity in tt events using a veto on additional central jet activity is presented.