Measurement of the w boson polarization in top quark decays with the ATLAS detector
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CitationADD, G., ABBOTT, B., ABDALLAH, J., KHALEK, S.A., ABDELALIM, A.A., ABDINOV, O., ATLAS Collaboration. (2012). Measurement of the w boson polarization in top quark decays with the ATLAS detector. Journal of Hight Energy Physics, Issue (6), 45p. http://dx.doi.org/10.1007/JHEP06(2012)088.
This paper presents measurements of the polarization of W bosons in top quark decays, derived from t (t) over bar events with missing transverse momentum, one charged lepton and at least four jets, or two charged leptons and at least two jets. Data from pp collisions at a centre-of-mass energy of 7 TeV were collected with the ATLAS experiment at the LHC and correspond to an integrated luminosity of 1.04 fb(-1). The measured fractions of longitudinally, left-and right-handed polarization are F-0 = 0.67 +/- 0.07, F-L = 0.32 +/- 0.04 and F-R = 0.01 +/- 0.05, in agreement with the Standard Model predictions. As the polarization of the W bosons in top quark decays is sensitive to the Wtb vertex Lorentz structure and couplings, the measurements were used to set limits on anomalous contributions to the Wtb couplings.