Top-quark charge asymmetry and polarization in $t\bar{t}W^\pm$ production at the LHC

F. Maltoni , M. L. Mangano , I. Tsinikos , M. Zaro (1)

1 LPTHE - Laboratoire de Physique Théorique et Hautes Energies

We study the charge asymmetry between the $t$ and $\bar t$ quark 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, $t \bar t W^{\pm}$ production can only occur via $q \bar q$ annihilation. As a result, the asymmetry between the $t$ and $\bar t$ generated at NLO in QCD is significantly larger than that of inclusive $t \bar t$ 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.

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]

F. Maltoni, M. L. Mangano, I. Tsinikos, M. Zaro. Top-quark charge asymmetry and polarization in $t\bar{t}W^\pm$ production at the LHC. 2014. ⟨hal-01024265⟩