Enhancement of h --> gamma gamma in the Two Higgs Doublet Model Type I

TL;DR

This paper investigates how the decay rate of the Higgs boson to two photons can be significantly increased in the Two Higgs Doublet Model Type I due to light charged scalars, under various theoretical constraints.

Contribution

It demonstrates that the h --> gamma gamma decay width can be enhanced in Type I THDM with light charged scalars, unlike in Type II, considering multiple theoretical constraints.

Findings

Decay width can be substantially larger than in the SM.

Light charged scalars around 100 GeV are viable in Type I.

Enhancement depends on Higgs potential parameters.

Abstract

We show that in the Two Higgs Doublet Model (THDM) Type I the partial decay width of h --> gamma gamma can be considerably larger than in Type II, due to light charged scalars with a mass about 100 GeV, which are not yet excluded in Type I. A possible enhancement of the width compared to the SM is analyzed for different Higgs potentials, subject to constraints from tree-level unitarity, vacuum stability and electroweak precision tests.