Masses of physical scalars in two Higgs doublet models

TL;DR

This paper derives bounds on scalar masses in various two Higgs doublet models by applying naturalness criteria and experimental constraints, generalizing the Veltman conditions beyond the Standard Model.

Contribution

It introduces a set of mass and coupling relations in 2HDMs based on quadratic divergence cancellation, extending the Veltman conditions to multiple model types.

Findings

Bounds on masses of additional scalars in 2HDMs

Relations among scalar masses and couplings

Constraints consistent with observed 125 GeV Higgs

Abstract

We find bounds on scalar masses resulting from a criterion of naturalness, in a broad class of two Higgs doublet models (2HDMs). Specifically, we assume the cancellation of quadratic divergences in what are called the type I, type II, lepton-specific and flipped 2HDMs, with an additional U(1) symmetry. This results in a set of relations among masses of the physical scalars and coupling constants, a generalization of the Veltman conditions of the Standard Model. Assuming that the lighter $CP$-even neutral Higgs particle is the observed scalar particle of mass $\sim$125 GeV, and imposing further the constraints from the electroweak T-parameter, stability, and perturbative unitarity, we calculate the range of the mass of each of the remaining physical scalars.