Measurement of top quark polarization in top-antitop events from proton- proton collisions at root s=7 TeV using the ATLAS Detector
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KünyeAad, G, Abajyan, T., Abbott, B., Abdallah, J., Abdel Khalek, S., Abdinov, O. ... ATLAS Collaboration. (2013). Measurement of top quark polarization in top-antitop events from proton- proton collisions at root s=7 TeV using the ATLAS Detector. Physical Review Letters, 111 (23), pp. 232002/1-232002/19. http://dx.doi.org/10.1103/PhysRevLett.111.232002.
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 root s = 7 TeV. Final states containing one or two isolated leptons ( electrons or muons) and jets are considered. Two measurements of alpha P-l, 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, alpha P-l(CPC) = -0: 035 +/- 0: 014(stat) +/- 0: 037(syst) and alpha P-l(CPV) = 0: 020 +/- 0: 016(stat)(-0.017)(+0.013)(syst), are in good agreement with the standard model prediction of negligible top quark polarization.