Abstract
We present a study of singlet-doublet vector-like leptonic dark matter (DM) in the framework of two Higgs doublet model (2HDM), where the dark sector is comprised of one doublet and one singlet vectorlike fermions (VLFs). The DM, that arises as an admixture of the neutral components of the VLFs, is stabilized by an imposed discrete symmetry $\mathcal{Z}_2^{'}$ . We test the viability of the model in the light of observations from PLANCK and recent limits on spin-independent direct detection experiments, and search for its possible collider signals. In addition, we also look for the stochastic gravitational wave (GW) signatures resulting from strong first order phase transition due to the presence of the second Higgs doublet. The model thus offers a viable parameter space for a stable DM candidate that can be probed from direct search, collider and GW experiments.
Highlights
Despite strong evidence of the existence of dark matter (DM) from several astrophysical and cosmological observations like rotation curves of spiral galaxies [1,2], the bullet cluster [3], gravitational lensing [4], etc., the particle nature of DM is unknown to date
We present a study of singlet-doublet vectorlike leptonic dark matter (DM) in the framework of the twoHiggs-doublet model (2HDM), where the dark sector is comprised of one doublet and one singlet vectorlike fermion (VLF)
We have proposed a singlet-doublet fermionic DM model, where the lightest fermion, emerging as a singletdoublet admixture of VLFs, can be a viable DM candidate (ψ1)
Summary
Despite strong evidence of the existence of dark matter (DM) from several astrophysical and cosmological observations like rotation curves of spiral galaxies [1,2], the bullet cluster [3], gravitational lensing [4], etc., the particle nature of DM is unknown to date. As we shall see, due to the presence of the second Higgs doublet, the bound from a direct search is less stringent. This is possible due to some destructive interference between the scalar-mediated direct search diagrams. Even in the absence of such destructive interference, a small direct search cross section is still conceivable due to the suppression coming from the heavy Higgs mass and small scalar mixing. This provides some freedom of choosing a moderate sin θ.
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