Interpretations and implications of the top quark rapidity asymmetries AFBt and AFBℓ

Forward-backward asymmetries AFBt and AFBℓ are observed in the top-quark t rapidity distribution and in the rapidity distribution of charged leptons ℓ from top-quark decay at the Tevatron proton-antiproton collider, and a charge asymmetry A_C is seen in proton-proton collisions at the Large Hadron Collider (LHC). In this paper, we update our previous studies of the Tevatron asymmetries using the most recent data. We provide expectations for A_C at the LHC based first on simple extrapolations from the Tevatron, and second based on new physics models that can explain the Tevatron asymmetries. We examine the relationship of the two asymmetries AFBt and AFBℓ. We show their connection through the (V-A) spin correlation between the charged lepton and the top quark with different polarization states. We show that the ratio of the two asymmetries provides independent insight into the physics interpretation of the top-quark asymmetry. We emphasize the value of the measurement of both asymmetries, and we conclude that a model which produces more right-handed than left-handed top quarks is suggested by the present Tevatron data.