Probing the CP properties of top Yukawa coupling at an $e^+e^-$ collider

Understand

We study consequences of CP violation in the $ht\bar{t}$ Yukawa coupling through the process $e^+e^- \to$ $h(125)t\bar{t}$.

• The helicity amplitudes are calculated in the $t\bar{t}$ rest frame, where the initial $e^+e^-$ current and the final Higgs boson have the same three-momentum.
• CP-violating asymmetries appear not only in the azimuthal angle between the $e^+e^-$ plane and the $t\bar{t}$ plane about the Higgs momentum direction, but also in the correlated decay angular distributions of $t$ and $\bar{t}$.
• Complete description of the production and decay angular distributions are obtained analytically, including both leptonic and hadronic decays of $t$ and $\bar{t}$.