Associated production of a top-quark pair with vector bosons at NLO in QCD: impact on $t \bar{t} H$ searches at the LHC

TL;DR

This paper provides next-to-leading order QCD predictions for top-quark pair production with vector bosons at the LHC, analyzing cross sections, asymmetries, uncertainties, and implications for Higgs searches.

Contribution

It offers the first comprehensive NLO QCD calculations for $t\bar{t}V$ and $t\bar{t}VV$ processes, including differential distributions and collider energy extrapolations.

Findings

NLO predictions reduce theoretical uncertainties.

Cross sections increase with collider energy up to 100 TeV.

Matching to parton shower helps estimate background contributions for Higgs analyses.

Abstract

We study the production of a top-quark pair in association with one and two vector bosons, $t \bar t V$ and $t \bar t VV$ with $V=\gamma, Z, W^\pm$, at the LHC. We provide predictions at next-to-leading order in QCD for total cross sections and top-quark charge asymmetries as well as for differential distributions. A thorough discussion of the residual theoretical uncertainties related to missing higher orders and to parton distribution functions is presented. As an application, we calculate the total cross sections for this class of processes (together with $t \bar t H$ and $t \bar t t \bar t$ production) at hadron colliders for energies up to 100 TeV. In addition, by matching the NLO calculation to a parton shower, we determine the contribution of $t \bar t V$ and $t \bar t VV$ to final state signatures (two-photon and two-same-sign-, three- and four-lepton) relevant for $t \bar t H$ analyses at the Run II of the LHC.