Abstract
We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same SU(3)L multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom.
Highlights
Interesting alternatives to CDM candidates, keV sterile neutrinos are usually overproduced in simplified models [18]
The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom
The study of keV neutrino dark matter has been discussed elsewhere in simplified models, our goal here is to embed this mechanism in a UV complete model, which is well motivated for other theoretical reasons as family replication [23] and electric charge quantization [24, 25]
Summary
This discrete symmetry (Z2) will play an important role in the dark sector of the model, as we shall see. With such matter and scalar content we build the following Yukawa interactions invariant under the gauge symmetry,. Concerning U 0, despite of being an interesting candidate, it does not provide the correct abundance (it is under-abundant), while νR did not receive any attention until now In other words, this is the first time that right-handed neutrino is being treated as dark matter in the 331νR. Before considering νR as dark matter candidate we discuss how to generate masses for the neutrinos in the model
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