Seungwon Baek, P. Ko, Wan-Il Park
Assuming ({\it i}) the seesaw mechanism works for neutrino masses and mixings, ({\it ii}) dark matter is absolutely stable due to unbroken $U(1)_X$ dark gauge symmetry, and ({\it iii}) the singlet fields ($H^\dagger H$ and $N_R$) are portal to the dark sector, we construct a simple model which is consistent with all the cosmological observations as well as terrestrial experiments available as of now, including leptogenesis, extra dark radiation of $\sim 6 %$ with respect to the contribution of a neutrino species, Higgs inflation, small and large scale structure formation, and current relic density of scalar DM ($X$). The electroweak (EW) vacuum of this model is stable up to Planck scale for $m_H = 125$ GeV without any other new physics. The Higgs signal strength is equal to one as in the SM for unbroken $U(1)_X$ case with a scalar dark matter, but it could be less than one if the dark matter is a dark sector fermion or if $U(1)_X$ is spontaneously broken, because of a mixing with a new neutral scalar boson in the models. Detailed study of Higgs properties at the LHC would shed light on the models described in this work.
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http://arxiv.org/abs/1303.4280
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