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

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.Comment: 22 pages, 3 tables, 6 figures. Version accepted for publication in JHE

A simplified 2HDM with a scalar dark matter and the galactic center gamma-ray excess

Due to the strong constrain from the LUX experiment, the scalar portal dark matter can not generally explain a gamma-ray excess in the galactic center by the annihilation of dark matter into $b\bar{b}$. With the motivation of eliminating the tension, we add a scalar dark matter to the aligned two-Higgs-doublet model, and focus on a simplified scenario, which has two main characteristics: (i) The heavy CP-even Higgs is the discovered 125 GeV Higgs boson, which has the same couplings to the gauge bosons and fermions as the SM Higgs. (ii) Only the light CP-even Higgs mediates the dark matter interactions with SM particles, which has no couplings to $WW$ and $ZZ$, but the independent couplings to the up-type quarks, down-type quarks and charged leptons. We find that the tension between $_{SS\to b\bar{b}}$ and the constraint from LUX induced by the scalar portal dark matter can go away for the isospin-violating dark matter-nucleon coupling with $-1.0< f^n/f^p<0.7$, and the constraints from the Higgs search experiments and the relic density of Planck are also satisfied.Comment: 12 pages, 3 figures, 1 table; reference adde

Status of the aligned two-Higgs-doublet model confronted with the Higgs data

Imposing the theoretical constraints from vacuum stability, unitarity and perturbativity as well as the experimental constraints from the electroweak precision data, flavor observables and the non-observation of additional Higgs at collider, we study the implications of available Higgs signals on a two-Higgs-doublet model with the alignment of the down-type quarks and charged lepton Yukawa coupling matrices. Compared to the four traditional types of two-Higgs-doublet models, the model has two additional mixing angles $\theta_d$ and $\theta_l$ in the down-type quark and charged lepton Yukawa interactions. We find that the mixing angle $\theta_d$ can loose the constraints on $sin(\beta-\alpha)$, $tan\beta$ and $m_{H^{\pm}}$ sizably. The model can provide the marginally better fit to available Higgs signals data than SM, which requires the Higgs couplings with gauge bosons, $u\bar{u}$ and $d\bar{d}$ to be properly suppressed, and favors (1 <\theta_d< 2, 0.5 <\theta_l< 2.2) for $m_h=$ 125.5 GeV and (0.5 <\theta_d< 2, 0.5 <\theta_l< 2.2) for $m_H=$ 125.5 GeV. However, these Higgs couplings are allowed to have sizable deviations from SM for ($m_h=$ 125.5 GeV, 125.5 $\leq m_H\leq$ 128 GeV) and (125 GeV $\leq m_h\leq$ 125.5 GeV, $m_H=$ 125.5 GeV).Comment: 21 pages, 9 figures and 3 tables. Final version appeared in JHE

LHC diphoton and Z+photon Higgs signals in the Higgs triplet model with Y=0

We study the implications of the LHC diphoton and Z+photon Higgs signals on the Higgs triplet model with Y=0. We discuss three different scenarios: (i) the observed boson is the light Higgs boson $h$; (ii) it is the heavy Higgs boson $H$; (iii) the observed signal is from the almost degenerate $h$ and $H$. We find that the inclusive Higgs diphoton rates in the first two scenarios can be enhanced or suppressed compared to the SM value, which can respectively fit the ATLAS and CMS diphoton data within $1\sigma$ range. The inclusive $ZZ^*$ rates are suppressed, which are outside $1\sigma$ range of ATLAS data and within $1\sigma$ range of CMS data. Meanwhile, another CP-even Higgs boson production rate can be suppressed enough not to be observed at the collider. For the third scenario, the Higgs diphoton rate is suppressed, which is outside $1\sigma$ range of ATLAS data, and the $ZZ^*$ rate equals to SM value approximately. In addition, we find that the two rates of $h\to \gamma\gamma$ and $h\to Z\gamma$ have the positive correlations for the three scenarios.Comment: 16 pages, 8 figures. Update of Higgs data, references added. Final version appeared in JHE

130 GeV gamma-ray line and enhancement of h→γγh\to\gamma\gamma in the Higgs triplet model plus a scalar dark matter

With a discrete $Z_2$ symmetry being imposed, we introduce a real singlet scalar $S$ to the Higgs triplet model with the motivation of explaining the tentative evidence for a spectral feature at $E_\gamma$ = 130 GeV in the Fermi LAT data. The model can naturally satisfy the experimental constraints of the dark matter relic density and direct detection data from Xenon100. The doubly charged and one charged scalars can enhance the annihilation cross section of $SS\to\gamma\gamma$ via the one-loop contributions, and give the negligible contributions to the relic density. $_{SS\to\gamma\gamma}$ for $m_{S}=130$ GeV can reach \ord(1)\times10^{-27} cm^3 s^{-1} for the small charged scalar masses and the coupling constant of larger than 1. Besides, this model also predict a second photon peak at 114 GeV from the annihilation $SS\to\gamma Z$, and the cross section is approximately 0.76 times that of $SS\to\gamma \gamma$, which is below the upper limit reported by Fermi LAT. Finally, the light charged scalars can enhance LHC diphoton Higgs rate, and make it to be consistent with the experimental data reported by ATLAS and CMS.Comment: 15 pages, 4 figure