Abstract
In this work we consider a model for particle dark matter where an extra inert Higgs doublet and an additional scalar singlet is added to the Standard Model (SM) Lagrangian. The dark matter candidate is obtained from only the inert doublet. The stability of this one component dark matter is ensured by imposing a $Z_2$ symmetry on this additional inert doublet. The additional singlet scalar has a vacuum expectation value (VEV) and mixes with the Standard Model Higgs doublet resulting in two CP even scalars $h_1$ and $h_2$. We treat one of these scalars, $h_1$, to be consistent with the SM Higgs like boson of mass around 125 GeV reported by the LHC experiment. These two CP even scalars affect the annihilation cross-section of this inert doublet dark matter resulting in a larger dark matter mass region that satisfies the observed relic density. We also investigate the $h_1 \rightarrow \gamma\gamma$ and $h_1 \rightarrow \gamma Z$ processes and compared these with LHC results. This is also used to constrain the dark matter parameter space in the present model. We find that the dark matter candidate in the mass region $\frac {m_1} {2} < m_H < m_W$ GeV ($m_1 = 125$ GeV, mass of $h_1$) satisfies the recent bound from LUX direct detection experiment.
Highlights
We found that the region of the dark matter (DM) parameter space for the case of the Higgs to diphoton signal strength predicted by ATLAS with 95 % CL is completely ruled out as the allowed DM mass region in the model cannot satisfy the latest direct detection bounds from XENON100 and LUX experiments
In this work we have proposed a model for dark matter where we consider an extended two Higgs doublet model with an additional singlet scalar
We extensively explored the scalar sector of the model and studied the signal strengths Rγ γ and Rγ Z for the Standard Model (SM)-like Higgs (h1) in the model
Summary
The CDMS [43,44] experiment claimed to have observed three potential signals of dark matter at low mass region (∼8 GeV) Direct detection experiments such as DAMA [45,46], CoGeNT [47] and CRESST [48] provide bounds on dark matternucleon scattering cross sections for different dark matter masses. We impose a discrete Z2 symmetry, under which all SM particles and the singlet scalar S are even while the inert doublet is odd This ensures the stability of the LIP (denoted as H ) of the inert doublet to remain stable and serve as a viable dark matter candidate. We evaluate the direct detection scattering cross section σSI with the resulting constrained parameters for different LIP masses m H and investigate the regions in σSI–m H plane that satisfy the bounds from experiments like LUX, XENON etc.
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