Renormalization of the C2HDM with FeynMaster 2

TL;DR

This paper details the one-loop electroweak renormalization of the CP-violating 2-Higgs-Doublet Model using FeynMaster 2, highlighting the unique process due to CP violation and the model's complex counterterm structure.

Contribution

It introduces a systematic renormalization procedure for the C2HDM, utilizing FeynMaster 2 for automatic derivation of Feynman rules and counterterms, and discusses gauge-independent process analysis.

Findings

Successful derivation of counterterms for C2HDM

Demonstration of gauge-independent NLO process analysis

Validation of FeynMaster 2 as a tool for model renormalization

Abstract

We present the one-loop electroweak renormalization of the CP-violating 2-Higgs-Doublet Model with softly broken $\mathbb{Z}_2$ symmetry (C2HDM). The existence of CP violation in the scalar sector of the model leads to a quite unique process of renormalization, since it requires the introduction of several non-physical parameters. The C2HDM will thus have more independent counterterms than independent renormalized parameters. As a consequence, different combinations of counterterms can be taken as independent for the same set of independent renormalized parameters. We compare the behaviour of selected combinations in specific NLO processes, which are assured to be gauge independent via a simple prescription. FeynMaster 2 is used to derive the Feynman rules, counterterms and one-loop processes in a simultaneously automatic and flexible way. This illustrates its use as an ideal tool to renormalize models such as the C2HDM and investigate them at NLO.