Measurements of $\mathrm{t\bar{t}}H$ Production and the CP Structure of the Yukawa Interaction between the Higgs Boson and Top Quark in the Diphoton Decay Channel

The CMS collaboration
Phys.Rev.Lett. 125 (2020) 061801, 2020.

Abstract
The first observation of the $\mathrm{t\bar{t}}$H process in a single Higgs boson decay channel with the full reconstruction of the final state (H$\to\gamma\gamma$) is presented, with a significance of 6.6 standard deviations ($\sigma$). 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 3.2$\sigma$. The measurements are based on a sample of proton-proton collisions at a center-of-mass energy $\sqrt{s} =$ 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 $\mathrm{t\bar{t}}$H process is measured to be $\sigma_{\mathrm{t\bar{t}H}}\mathcal{B}_{\gamma\gamma} =$ 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 $f^{\mathrm{Htt}}_\mathrm{CP} =$ 0.00 $\pm$ 0.33.

  • Table 1

    summary

    10.17182/hepdata.94286.v1/t1

    measured cross section times branch ratio

  • Table 2

    summary

    10.17182/hepdata.94286.v1/t2

    measured cross section times branch divided by SM prediction

  • Table 3

    summary

    10.17182/hepdata.94286.v1/t3

    Observed significance

  • Table 4

    summary

    10.17182/hepdata.94286.v1/t4

    constraint on CP-odd contribution at 68% CL

  • Table 5

    summary

    10.17182/hepdata.94286.v1/t5

    exclusion significance on pure CP odd contribution

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