Abstract
We study a model with a hidden sector coupled to keV scale sterile neutrinos. Due to nontrivial dynamics of this sector, the initially massless sterile neutrino acquires a nonzero mass at some temperature corresponding to the phase transition in the hidden sector. It shifts the onset of oscillations in plasma to later times, so that the final abundance of sterile neutrinos is strongly suppressed. We argue that in this model various cosmological and astrophysical bounds can be significantly alleviated opening new perspectives for ground-based experiments such as Troitsk ν-mass and KATRIN in the large mixing region.
Highlights
Introduction of sterile neutrinos is one of the most popular ways to minimally extend the StandartModel (SM) of particle physics [1]
We argue that the sterile neutrino production via oscillations in some phenomenological models can be significantly suppressed
We assume that the active neutrino number does not decrease dramatically by conversion to the sterile neutrinos. It is valid for small enough mixing angles both above and below the freeze-out of active neutrinos occurred at Tν, f ∼ 2 MeV
Summary
Introduction of sterile neutrinos is one of the most popular ways to minimally extend the Standart. The active neutrinos are effectively produced via oscillations in the early Universe and can overproduce the DM today [2, 3]. There are fairly weak bounds from direct searches, sin2(2θ) < 10−3 − 10−2, valid for any sterile neutrino abundance. We argue that the sterile neutrino production via oscillations in some phenomenological models can be significantly suppressed. Such dumping depends only on specific properties of the hidden sector. In the early Universe the most effective generation of sterile neutrinos through the activesterile mixing happens at. If oscillations start at T ∼ Tc ≪ Tmax, where Tc denotes the critical temperature of the onset of scalar field oscilations, the present abundance of sterile neutrinos will be depleted.
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