Abstract
At the LHC, top quark pairs are dominantly produced from gluons, making it difficult to measure the top quark forward-backward asymmetry. To improve the asymmetry measurement, we study variables that can distinguish between top quarks produced from gluons and those from quarks: the invariant mass of the top pair, the rapity of the top-antitop system in the lab frame, the rapity of the top quark in the top quark polarization and the top-antitop spin correlation. We combine all the variables in a likelihood discriminant method to separate gluon-initiated events from quark-initiated events. We apply our method on models including G-prime’s and W-prime’s motivated by the recent observation of a large top quark forward-backward asymmetry at the Tevatron. We have found that the significance of the asymmetry measurement can be enhanced by 10% to 30%. At the same time, the central values of the asymmetry increase by 40% to 100%. We have also obtained the best spin quantization axes for studying top quark polarization as well as spin-correlation for the new physics models.
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Bai, Y., Han, Z. Improving the top quark forward-backward asymmetry measurement at the LHC. J. High Energ. Phys. 2012, 135 (2012). https://doi.org/10.1007/JHEP02(2012)135
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DOI: https://doi.org/10.1007/JHEP02(2012)135