Measurement of the top quark pair production charge asymmetry in proton-proton collisions at 7 TeV using the ATLAS detector

Abstract

This letter presents a measurement of the top quark pair (tt) production charge asymmetry Ac using 4.7 fb-1 of proton-proton collisions at a centre-of-mass energy of 7 TeV collected by the ATLAS detector at the LHC. A tt-enriched sample of events with 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, is selected. A likelihood fit is used to reconstruct the tt event kinematics. A Bayesian unfolding procedure is employed to estimate Ac at the parton-level. The measured value of the tt production charge asymmetry is 0.006 +/- 0.010, where the uncertainty includes both the statistical and the systematic components. Differential Ac measurements as a function of the invariant mass, the rapidity and the transverse momentum of the tt-system are also presented. In addition, Ac is measured for a subset of events with large tt velocity, where physics beyond the Standard Model could contribute. All measurements are consistent with the Standard Model predictions.

22 pages plus author list (44 pages total), 3 figures, 9 tables, submitted to JHEP. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2012-17/

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