Categorization of two-loop Feynman diagrams in the

The $e^+e^- \rightarrow ZH$ process is the dominant for Higgs boson production at future factory. In order to match analysis on properties with highly precise experiment data, it will be crucial include theoretical prediction full next-to-next-to-leading electroweak effect in rate $\sigma(e^+e^-\rightarrow ZH)$. this inspiring work, we categorize two-loop Feynman diagrams of $\mathcal O(\alpha^2)$ correction into 6 categories according relevant topological structures. Although 25377 contribute total, number most challenging seven denominators 2250, which contain only 312 non-planar 155 independent types. This categorization could a valuable reference complete calculation future.