Restricting the parameter space of Type-II Two Higgs Doublet Models with CP violation

TL;DR

This paper investigates the parameter space of the CP-violating Type-II Two Higgs Doublet Model, showing how experimental and theoretical constraints limit Higgs masses and decay signals, revealing potential CP violation signatures.

Contribution

It provides a detailed analysis of the constrained parameter space of the CP-violating 2HDM, highlighting the impact of experimental bounds on Higgs masses and decay channels.

Findings

CP-violating phases restrict parameter space significantly.

Heavy Higgs masses are bounded and nearly degenerate.

Distinct decay signals indicate CP violation.

Abstract

We explore the parameter space of the type-II two-Higgs-doublet model with softly broken Z2 symmetry, allowing for CP violation in the scalar potential. Imposing theory-motivated and experimentally-driven constraints, we show that as the CP-violating phases are increased, only small regions of parameter space survive, including regions slightly away from the alignment limit. Electroweak oblique parameters and electric dipole moments emerge as most restrictive constraints. We show that imposing these constraints (as well as theoretical bounds such as perturbativity) the masses of the charged and heavy neutral Higgs, unlike in the CP conserving case, are bound from above and below. In particular, the heavy neutral Higgs masses are almost degenerate. In this parameter space region we highlight the relevant decay signals of the heavy neutral Higgs, involving both Zh and WW=ZZ, indicative of CP violation in the model.