Unitarity bounds for all symmetry-constrained 3HDMs

TL;DR

This paper derives unitarity bounds for all symmetry-constrained three-Higgs-doublet models (3HDMs) by calculating scattering amplitude limits and introduces a general principal minors method for analyzing large scattering matrices.

Contribution

It provides the first comprehensive unitarity bounds for all symmetry-constrained 3HDMs and proposes a new, efficient method for analyzing large scattering matrices in such models.

Findings

Explicit bounds for all symmetry-constrained 3HDMs derived.

A novel principal minors method for scattering matrix analysis introduced.

Method applicable to large models beyond 3HDM.

Abstract

Models with three Higgs doublets (3HDM) are the source of much recent activity, for they are key components of many solutions to the problems of the Standard Model; from extra sources of CP violation to Dark Matter candidates. We compute explicitly the theoretical bounds for all symmetry-constrained 3HDM arising from the perturbative unitarity of two-to-two scattering amplitudes. In addition, we propose a method based on principal minors that foregoes diagonalization and which is preferable in all models (not only 3HDM) dealing with large scattering matrices.