125 GeV Higgs bosons in two-Higgs-doublet models

TL;DR

This paper investigates how two-Higgs-doublet models can enhance Higgs boson signals around 125 GeV, considering experimental constraints and analyzing different model types for their potential to explain observed excesses.

Contribution

It provides a detailed analysis of the maximum possible signal enhancements in 2HDMs near 125 GeV, accounting for theoretical and experimental constraints, and compares Type I and Type II models.

Findings

Type II model can enhance di-photon rate by 2-3 times but with larger ZZ or tau-tau signals.

Type I model can increase di-photon signal up to 1.3 times with moderate ZZ signal.

Constraints from vacuum stability, unitarity, and perturbativity limit signal enhancements.

Abstract

Moriond 2013 ALTAS data at 125 GeV state appears to exhibit a substantial excess in the di-photon final state and in the ZZ decaying to four lepton channel, whereas which are more or less SM-like rate observed by CMS MVA analysis. We examine the maximum Higgs signal enhancements that can be achieved in the 2HDM when either a single Higgs or more than one Higgs have mass(es) near 125 GeV. In general, the constraints of vacuum stability, unitarity and perturbativity play the key role in restricting possibilities of signal enhancement. The Type II model allows for an enhancement in the di-photon rate (relative to the SM) of the order of 2-3 but associated with an even larger ZZ or too large \tau\tau signal. In contrast, the maximal value of the di-photon signal in the Type I model can reach the order of 1.3 for which the ZZ signal is of order 1.