Indirect CP probes of the Higgs--top-quark interaction at the LHC

The precise determination of the Higgs boson CP properties is among the most important goals for existing and future colliders. In this work, we evaluate existing constraints on the CP nature of the Higgs interaction with top quarks taking into account all relevant inclusive and differential Higgs boson measurements. We study the model dependence of these constraints by allowing for deviations from the SM predictions also in the Higgs couplings to massive vector boson, photons, and gluons. Additionally, we evaluate the future prospects for constraining the CP nature of the top-Yukawa coupling by total rate measurements. In this context, we propose an analysis strategy for measuring tH production at the HL-LHC without relying on assumptions about the Higgs CP character.