Study of the heavy CP-even Higgs with mass 125 GeV in two-Higgs-doublet models at the LHC and ILC

TL;DR

This paper investigates the possibility that the 125 GeV Higgs is the heavy CP-even Higgs in two-Higgs-doublet models, analyzing current constraints and future collider sensitivities to Higgs couplings.

Contribution

It explores the parameter space of various two-Higgs-doublet models assuming the 125 GeV Higgs is the heavy CP-even Higgs and projects future collider constraints on model parameters.

Findings

Future colliders can exclude wrong-sign Yukawa regions at 2σ.

Higgs couplings will be tightly constrained to SM values.

Future experiments will significantly restrict the parameter space of two-Higgs-doublet models.

Abstract

We assume that the 125 GeV Higgs discovered at the LHC is the heavy CP-even Higgs of the two-Higgs-doublet models, and examine the parameter space in the Type-I, Type-II, Lepton-specific and Flipped models allowed by the latest Higgs signal data, the relevant experimental and theoretical constraints. Further, we show the projected limits on $\tan\beta$, $\sin(\beta-\alpha)$, $Hf\bar{f}$ and $HVV$ couplings from the future measurements of the 125 GeV Higgs at the LHC and ILC, including the LHC with integrated luminosity of 300 fb$^{-1}$ (LHC-300 fb$^{-1}$) and 3000 fb$^{-1}$ (LHC-3000 fb$^{-1}$) as well as the ILC at $\sqrt{s}=250$ GeV (ILC-250 GeV), $\sqrt{s}=500$ GeV (ILC-500 GeV) and $\sqrt{s}=1000$ GeV (ILC-1000 GeV). Assuming that the future Higgs signal data have no deviation from the SM expectation, the LHC-300 fb$^{-1}$, LHC-3000 fb$^{-1}$ and ILC-1000 GeV can exclude the wrong-sign Yukawa coupling regions of the Type-II, Flipped and Lepton-specific models at the $2\sigma$ level, respectively. The future experiments at the LHC and ILC will constrain the Higgs couplings to be very close to SM values, especially for the $HVV$ coupling.