Measurement of the Charge Asymmetry in Dileptonic Decays of Top Quark Pairs in pp Collisions at √s=7 TeV Using the ATLAS Detector

A measurement of the top-antitop (tt̅) charge asymmetry is presented using data corresponding to an integrated luminosity of 4.6 fb⁻¹ of LHC pp collisions at a centre-of-mass energy of 7 TeV collected by the ATLAS detector. Events with two charged leptons, at least two jets and large missing transverse momentum are selected. Two observables are studied: A^(ℓℓ)(C) based on the identified charged leptons, and A^(tt̅)(C), based on the reconstructed tt̅ final state. The asymmetries are measured to be A^(ℓℓ)(C) = 0.024 ± 0.015 (stat.) ± 0.009 (syst.), A^(tt̅)(C) = 0.021 ± 0.025 (stat.) ± 0.017 (syst.). The measured values are in agreement with the Standard Model predictions.