Measurement of top quark polarization in top-antitop events from proton-proton collisions at sqrts=7 TeV using the ATLAS detector

This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7 fb-1 of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at ?????????s=7 TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements of ???????????????P, the product of the leptonic spin-analyzing power and the top quark polarization, are performed assuming that the polarization is introduced by either a CP conserving or a maximally CP violating production process. The measurements obtained, ???????????????PCPC=-0.035??????0. 014(stat)??????0.037(syst) and ???????????????PCPV=0. 020??????0.016(stat)-0.017+0.013(syst), are in good agreement with the standard model prediction of negligible top quark polarization. ?????? 2013 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.