CMS CollaborationShchutska, Lesya2023-10-032023-10-032023-10-03202010.1103/PhysRevLett.125.061801https://infoscience.epfl.ch/handle/20.500.14299/201288The first observation of the t¯tH process in a single Higgs boson decay channel with the full reconstruction of the final state (H→γγ) is presented, with a significance of 6.6 standard deviations (σ). The CP structure of Higgs boson couplings to fermions is measured, resulting in an exclusion of the pure CP-odd structure of the top Yukawa coupling at 3.2σ. The measurements are based on a sample of proton-proton collisions at a center-of-mass energy √s=13  TeV collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 137  fb−1. The cross section times branching fraction of the t¯tH process is measured to be σt¯tHBγγ=1.56+0.34−0.32  fb, which is compatible with the standard model prediction of 1.13+0.08−0.11  fb. The fractional contribution of the CP-odd component is measured to be fHttCP=0.00±0.33.text::journal::journal article::research article