Speaker
Description
Measurements of the Higgs boson production in association with top quarks provide a direct probe of the Higgs-top Yukawa coupling, a key parameter in the Standard Model. This talk presents the latest ATLAS results on ttH and tH production using the full Run 2 dataset of 140 fb⁻¹ at √s = 13 TeV, with a focus on the multi-lepton final state. The measured ttH signal strength is σ_ttH/σ_SM = 0.63⁺⁰·²⁰₋₀·¹⁹, corresponding to an observed significance of 3.3σ. Furthermore, the CP structure of the top-Higgs Yukawa coupling is probed through a combined analysis of ttH and tH events. Values of the CP mixing angle |α| > 62° are excluded at 68% confidence level, setting important limits on possible CP-odd contributions to the Higgs-top interaction, which is closely connected to the CP violation required to explain the baryon asymmetry of the universe.
