NLO QCD corrections to top quark pair production in association with one hard jet at hadron colliders

TL;DR

This paper calculates next-to-leading order QCD corrections for top quark pair production with an additional jet at hadron colliders, providing detailed distributions and confirming a reduction in the forward-backward asymmetry at the Tevatron.

Contribution

It introduces a method using generalized D-dimensional unitarity to compute these corrections, including top decays at leading order, and analyzes the impact on asymmetry predictions.

Findings

Confirmed reduction of top quark forward-backward asymmetry at NLO

Provided detailed kinematic distributions with realistic cuts

Validated the perturbative approach for asymmetry analysis

Abstract

We compute the QCD corrections to the production of a top quark pair in association with one hard jet at the Tevatron and the LHC, using the method of generalized D-dimensional unitarity. Top quark decays are included at leading order in perturbative QCD. We present kinematic distributions of top quark decay products in lepton plus jets and dilepton final states at the Tevatron and the LHC, using realistic selection cuts. We confirm a strong reduction of the top quark forward-backward asymmetry for the process ttbar+jet at the Tevatron at next-to-leading order, first observed by Dittmaier, Uwer and Weinzierl. We argue that there is a natural way to understand this reduction and that it does not imply a breakdown of the perturbative expansion for the asymmetry.