Light Higgs bosons in Two-Higgs-Doublet Models

TL;DR

This paper investigates the existence and detectability of light Higgs bosons below 60 GeV in two-Higgs-doublet models, analyzing parameter space viability and potential signals at the LHC.

Contribution

It demonstrates that light Higgs states in 2HDMs are phenomenologically viable and identifies experimental signatures for their detection.

Findings

Light Higgs bosons below 60 GeV are possible in 2HDMs.

Some parameter space regions are testable with current LHC data.

Light Higgs decays into c4^+ c4^- and bc^+ bc^- are promising detection channels.

Abstract

We explore the possibilities in two-Higgs-doublet models (2HDMs) of Type I and Type II for Higgs states with mass below about 60 GeV, i.e. less than half of the ~125 GeV mass of the observed SM-like Higgs boson. We identify the latter as either the lighter or the heavier CP-even state, h or H, and employ scans of the 2HDM parameter space taking into account all relevant theoretical and experimental constraints, including the most up-to-date Higgs signal strength measurements. We find that, in both Type I and Type II models, such light Higgs states are phenomenologically viable and can lead to interesting signatures. Part of the relevant parameter space may be testable with the existing 8 TeV LHC data, e.g. by looking for direct production of the light state via gg-fusion or bb-associated-production using its \tau^+ \tau^- and \mu^+ \mu^- decays at low invariant mass.