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We present a measurement of the charge asymmetry in top-antitop productionusing data corresponding to an integrated luminosity of $0.70 fb^{-1}$ ofproton-proton collisions at $\sqrt s = 7$ TeV collected by the ATLAS detector.The top pair events decaying semileptonically (lepton+jets channel) to eitheran electron or muon, missing transverse energy and at least four jets areselected. The reconstruction of the $t\bar{t}$ events was performed using akinematic likelihood approach. The difference of absolute values of top andantitop rapidities is used to define the charge asymmetry: $A_{C} = (N(|\DeltaY|>0) - N(|\Delta Y|<0)) / (N(|\Delta Y>0) + N(|\Delta Y|<0))$. To allowcomparisons with theory calculations, a Bayesian unfolding technique is appliedto correct the measured $|\Delta Y|$ distributions for acceptance and detectoreffects. The top charge asymmetry in both channels (e and mu) after correctionis measured to be: $A_{C} = -0.009 \pm 0.023 (stat) \pm 0.032 (syst)$ (e+jetschannel) and $A_{C} = -0.028 \pm 0.019 (stat) \pm 0.022 (syst)$ ($\mu$+jetschannel) giving a combined result of : $A_{C} = -0.024 \pm 0.016 (stat) \pm0.023 (syst)$. These results are compatible with the Standard Model predictionsof $A_{C}=0.006$.

Measurement of the charge asymmetry in top quark pair production in pp collisions at $\sqrt s = 7 $ TeV using the ATLAS detector