Polarized view of the top asymmetry

Abstract

Recent experimental results from the CDF collaboration which study the top forward-backward asymmetry have strengthened the case that new physics is playing a role in tt¯ production. Here, we propose a set of measurements, built from the charged lepton kinematics in semileptonic and fully leptonic tt¯ events, designed to further probe the underlying causes of this asymmetry both at the Tevatron and at the LHC. Using a set of conservative reference models, we find that measurements of the charged lepton asymmetry, top polarization, and tt¯ spin correlation can establish the existence of new physics and distinguish between competing models both at the Tevatron and the LHC. At the Tevatron, discrimination between models is possible at the 3σ level. At the LHC, we demonstrate that a top forward-backward asymmetry can be established at ≳3σ in the first ∼5  fb<sup>−1</sup> of data and show how competing explanations can be further disentangled.