Improving the Top Quark Forward-Backward Asymmetry Measurement at the LHC
arXiv:1106.5071 · doi:10.1007/JHEP02(2012)135
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 quarks and those from gluons: the invariant mass of the top pair, the rapidity of the top-antitop system in the lab frame, the rapidity of the top quark in the top-antitop rest frame, the top quark polarization and the top-antitop spin correlation. We combine all the variables in a likelihood discriminant method to separate quark-initiated events from gluon-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 improved by 10% to 30%. At the same time, the central values of the asymmetry increase by 40% to 100%. We have also analytically derived the best spin quantization axes for studying top quark polarization as well as spin-correlation for the new physics models.
26 pages, 11 figures
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- A New Twist on Top Quark Spin Correlations
- Discerning New Physics in Top-Antitop Production using Top Spin Observables at Hadron Colliders
- Light axigluon explanation of the Tevatron ttbar asymmetry and multijet signals at the LHC
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