Top-quark charge asymmetry and polarization in t(t)over-barW± production at the LHC

We study the charge asymmetry between the t and (t) over bar quarks at the LHC, when they are produced in association with a W boson. Though sizably reducing the cross section with respect to the inclusive production, requiring a W boson in the final state has two important implications. First, at leading order in QCD, t (t) over barW(+/-) production can only occur via q (q) over bar annihilation. As a result, the asymmetry between the t and (t) over bar generated at NLO in QCD is significantly larger than that of inclusive t (t) over bar production, which is dominated by gluon fusion. Second, the top quarks tend to inherit the polarization of the initial-state quarks as induced by the W-boson emission. Hence, the decay products of the top quarks display a sizable asymmetry already at the leading order in QCD. We study the relevant distributions and their uncertainties in the standard model, compare them to those obtained in a simple axigluon model and discuss prospects for measurements at the LHC and beyond. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license