We study Higgs boson production in association with a top quark and a W boson at the LHC. At NLO in QCD, tWH interferes with ttÂ¯H and a procedure to meaningfully separate the two processes needs to be employed. In order to define tWH production for both total rates and differential distributions, we consider the diagram removal and diagram subtraction techniques that have been previously proposed for treating intermediate resonances at NLO, in particular in the context of tW production. These techniques feature approximations that need to be carefully taken into account when theoretical predictions are compared to experimental measurements. To this aim, we first critically revisit the tW process, for which an extensive literature exists and where an analogous interference with ttÂ¯ production takes place. We then provide robust results for total and differential cross sections for tW and tWH at 13Â TeV, also matching short-distance events to a parton shower. We formulate a reliable prescription to estimate the theoretical uncertainties, including those associated to the very definition of the process at NLO. Finally, we study the sensitivity to a non-Standard-Model relative phase between the Higgs couplings to the top quark and to the W boson in tWH production.

Belgium

Federico Demartin

Germany

United States

Benedikt Maier

Fabio Maltoni

France

Kentarou Mawatari

Marco Zaro

tWH associated production at the LHC

We present a detailed study of Higgs boson production in association with a single top quark at the LHC, at next-to-leading order accuracy in QCD. We consider total and differential cross sections, at the parton level as well as by matching short distance events to parton showers, for both t -channel and s -channel production. We provide predictions relevant for the LHC at 13 TeV together with a thorough evaluation of the residual uncertainties coming from scale variation, parton distributions, strong coupling constant and heavy quark masses. In addition, for t -channel production, we compare results as obtained in the 4-flavour and 5-flavour schemes, pinning down the most relevant differences between them. Finally, we study the sensitivity to a non-standard-model relative phase between the Higgs couplings to the top quark and to the weak bosons.

Higgs production in association with a single top quarkÂ atÂ theÂ LHC

At the LHC the CP properties of the top-quark Yukawa interaction can be probed through Higgs production in gluon fusion or in association with top quarks. We consider the possibility for both CP-even and CP-odd couplings to the top quark to be present, and study CP-sensitive observables at next-to-leading order (NLO) in QCD, including parton-shower effects. We show that the inclusion of NLO corrections sizeably reduces the theoretical uncertainties, and confirm that di-jet correlations in H+2 jet production through gluon fusion and correlations of the top-quark decay products in tt¯H production can provide sensitive probes of the CP nature of the Higgs interactions.

Spain

Ben Page

Higgs characterisation at NLO in QCD: CP properties of the top-quark Yukawa interaction