Categorization of two-loop Feynman diagrams in the O(α^(2))correction to e^(+)e^(-)→ZH

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