Amr El-Zant, Shaaban Khalil, Arunansu Sil
We show that a standard model gauge singlet fermion field, with mass of order keV or larger, and involved in the inverse seesaw mechanism of light neutrino mass generation, can be a good warm dark matter candidate. Our framework is based on $B-L$ extension of the Standard Model and the construction ensures the absence of any mixing between active neutrinos and the aforementioned dark matter field. This circumvents the usual constraints on the mass of warm dark matter imposed from X-rays. We show that over-abundance of thermally produced warm dark matter (which nevertheless do not reach chemical equilibrium) can be reduced to an acceptable range in the presence of a moduli field decaying into radiation --- though only when the reheating temperature is low enough. Our warm dark matter candidate can also be produced non-thermally, directly from the decay of the moduli field during reheating. In this case, obtaining the right amount of relic abundance of our dark matter candidate, while keeping the reheating temperature high enough as to be consistent with Big Bang nuceosynthesis bounds, places constraints on the branching ratio for the decay of the moduli field into dark matter.
View original:
http://arxiv.org/abs/1308.0836
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