Joshuha Thomas-Wilsker

This article reviews recent cross-section measurements of tt¯ production in association with a photon, W or Z boson at the Large Hadron Collider (LHC). All measurements reviewed use proton–proton (pp) datasets collected by the ATLAS and CMS experiments between 2016 and 2018 from collisions at a centre-of-mass energy of 13 TeV during the LHC Run 2. Differential and inclusive cross-section measurements are discussed along with the constraints on the effective field theory operators accessible through each process. Finally, we discuss the potential for measurements of these processes at future colliders.

This note presents Monte Carlo generator comparisons of the ttbb and ttW processes at particle level. The aim is to compare the modelling of important backgrounds to ttH measurements in multi-lepton final states and in the ttH(H->bb) decay channel and the treatment of the associated theory uncertainties for a combination of the full Run-2 ttH results from ATLAS and CMS. As a first step, modelling and theory uncertainties as used in ATLAS an CMS are compared in the relevant analysis regions. Significant differences in the treatment of systematic uncertainties between the experiments have been observed in ttbb and ttW. As a first step, ATLAS and CMS agreed on a common reference value of the inclusive ttW cross section to allow direct comparisons between experiments.

This article reviews recent cross-section measurements of top-quark pair production in association with a photon, W or Z boson at the Large Hadron Collider (LHC). All measurements reviewed use proton-proton (pp) datasets collected by the ATLAS and CMS experiments between 2016 and 2018 from collisions at a centre-of-mass energy of 13 TeV during the LHC Run 2. Differential and inclusive cross-section measurements are discussed along with the constraints on the effective field theory operators accessible through each process. Finally, we discuss the potential for measurements of these processes at future colliders.