Top quark pair production in ATLAS

The Large Hadron Collider (LHC) is a top quark factory. Since March 2010, the ATLAS (A Toroidal LHC ApparatuS) [1] detector is recording data from proton-proton collisions at the LHC at the unprecedented centre of mass energy of 7 TeV. After QCD jets, W and Z bosons, the production of top quarks is the dominant process. The search for first top pairs candidate events and the related background studies using data-driven techniques are here reported using an integrated luminosity of 295 nb-1. Several candidate events are observed, in both semi-leptonic and di-leptonic channels. The properties of these events are described, and compared to the expectations from Monte-Carlo simulation.