The Top Quark Charge Asymmetry using 4.7fb$^{-1}$ at $\sqrt{s}$ =7 TeV with the ATLAS Detector

A summary of results for the top quark charge asymmetry $A_C$ measurements using 4.7 fb$^{-1}$ at $\sqrt{s}=7$ TeV in the dilepton and semileptonic channels are presented. Selected dilepton events are required to have exactly two leptons ($ee$,$e\mu$, or $\mu\mu$), large missing transverse momentum and at least two jets. Selected semileptonic events consist of a single lepton (electron or muon), missing transverse momentum, and at least four high transverse momentum jets, of which at least one is tagged as coming from a $b$-quark. Both analyses employ a likelihood fit to reconstruct the $t\bar{t}$ kinematics and an unfolding procedure to estimate the asymmetry at the parton level. Measured $t\bar{t}$ charge asymmetries are $A_C = 0.006 \pm 0.010$ (semileptonic), where the uncertainty includes both statistical and systematic components, $A_C = 0.057 \pm 0.024$ (stat.) $\pm$ 0.015 (syst.) (dilepton). The lepton-based asymmetry, as measured in the dilepton channel, is measured to be $A_C^{\ell\ell} = 0.023 \pm 0.012$ (stat.) $\pm$ 0.008 (syst.). All measurements are consistent with Standard Model predictions.