New Tools for Dissecting the General 2HDM

TL;DR

This paper develops new analytical tools to analyze the most general two Higgs doublet model (2HDM), focusing on theoretical constraints like unitarity, stability, and vacuum conditions, with implications for CP violation.

Contribution

It derives novel analytical expressions for the general 2HDM constraints, extending previous results to models without parity symmetry.

Findings

New analytical bounds for the general 2HDM

Insights into CP violation within these models

Implications for model viability and phenomenology

Abstract

Two Higgs doublet models (2HDM) provide the low energy effective field theory (EFT) description in many well motivated extensions of the Standard Model. It is therefore relevant to study their properties, as well as the theoretical constraints on these models. In this article we concentrate on three relevant requirements for the validity of the 2HDM framework, namely the perturbative unitarity bounds, the bounded from below constraints, and the vacuum stability constraints. In this study, we concentrate on the most general renormalizable version of the 2HDM -- without imposing any parity symmetry, which may be violated in many UV extensions. We derive novel analytical expressions that generalize those previously obtained in more restrictive scenarios to the most general case. We also discuss the phenomenological implications of these bounds, focusing on CP violation.