Democratic three Higgs-doublet models: the custodial limit and wrong-sign Yukawa

TL;DR

This paper explores novel features of democratic three Higgs-doublet models, focusing on the custodial limit and the potential for wrong-sign Yukawa couplings, revealing greater flexibility than two Higgs-doublet models.

Contribution

It introduces the custodial limit in democratic 3HDMs and demonstrates their expanded capacity for wrong-sign Yukawa couplings compared to 2HDMs.

Findings

Democratic 3HDMs can satisfy electroweak T-parameter constraints in the custodial limit.

They can realize all wrong-sign Yukawa configurations possible in 2HDMs.

Democratic 3HDMs offer more leeway in wrong-sign Yukawa scenarios than 2HDMs.

Abstract

We study two novel aspects of democratic 3HDMs -- the custodial limit and the possibility of wrong-sign Yukawa couplings. In the custodial limit, the democratic 3HDMs can easily negotiate the constraints from the electroweak $T$-parameter. We also uncover the possibility of having wrong-sign Yukawa couplings in democratic 3HDMs, as in the case of 2HDMs. We show that a democratic 3HDM encompasses all the wrong-sign possibilities entertained by 2HDMs, and has considerably more leeway in the wrong-sign limit as compared to the 2HDM case. Our study underscores the importance of reporting analysis in the kappa-formalism without any implicit assumptions on the signs of the kappas.