Abstract
We study production of keV scale sterile neutrinos with large mixing with the Standard Model sector [1]. Conventional mechanism of sterile neutrino generation in the early Universe leads to overproduction of the Dark Matter and strong X-ray signal from sterile neutrino decay. It makes anticipated groundbased experiments on direct searches of sterile-active mixing unfeasible. We argue that for models with a hidden sector coupled to the sterile neutrinos cosmological and astrophysical constraints can be significantly alleviated. In developed scenario a phase transition in the hidden sector modifies the standard oscillation picture and leads to significantly larger mixing angles, thus opening new perspectives for future neutrino experiments such as Troitsk v-mass and KATRIN. This work was made in collaboration with Fedor Bezrukov and Dmitry Gorbunov.
Highlights
Introduction of sterile neutrino is one of the most popular extension of the Standard Model (SM), see [2] for review
Mixing with active neutrino is usually considered to be very small, θ2 10−7. It leads to overproduction of the Dark Matter (DM) density today [4, 5]
We develop a new mechanism of sterile neutrino production in the early Universe
Summary
Introduction of sterile neutrino is one of the most popular extension of the Standard Model (SM), see [2] for review. Mixing with active neutrino is usually considered to be very small, θ2 10−7. Otherwise, it leads to overproduction of the Dark Matter (DM) density today [4, 5]. We argue that in the models with a hidden sector production of sterile neutrinos can be strongly suppressed. In the early Universe the most efficient sterile neutrino production via oscillations in plasma refers to temperatures [4, 9]. If oscillations are strongly suppressed at this temperature owing to non-trivial dynamics in the hidden sector, the final sterile neutrino abundance will be depleted. We focus on the natural idea that this suppression can be efficient in case of different sterile neutrino mass evolution at low and high temperatures.
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