Top-Quark Charge Asymmetry Goes Forward: Two New Observables for Hadron Colliders

TL;DR

This paper introduces two novel observables, the incline and energy asymmetries, to measure charge asymmetry in top-quark pair production with a jet at hadron colliders, enhancing detection capabilities.

Contribution

It proposes the incline and energy asymmetries as new tools to probe charge asymmetry in top-quark production, especially in quark-antiquark and quark-gluon channels.

Findings

Incline asymmetry improves access to partonic charge asymmetry.

Energy asymmetry enables probing quark-gluon channel at LHC.

Asymmetries up to -12% are achievable with cuts.

Abstract

We propose two new observables to measure the charge asymmetry in hadronic top-quark pair production in association with a hard jet. The incline asymmetry, based on the inclination between the planes of initial- and final-state momenta, probes the charge asymmetry in the quark-antiquark channel. Compared to the hitherto investigated rapidity asymmetries, the incline asymmetry provides improved access to the partonic charge asymmetry at both the Tevatron and the LHC. The energy asymmetry, based on the energy difference between top and antitop quarks, for the first time allows us to probe the charge asymmetry in the quark-gluon channel at the LHC. In quantum chromodynamics, asymmetries of up to -12% at the leading order are achievable with appropriate cuts. Top-pair plus jet production thus has the potential to become the discovery channel of the charge asymmetry in proton-proton collisions.