Sterile neutrinos, dark matter and Standard Model extended by right-handed neutrinos

TL;DR

This paper confirms the existence of a sterile neutrino with specific oscillation parameters, discusses its role as dark matter, and explores extending the Standard Model with right-handed neutrinos to explain cosmological phenomena.

Contribution

It provides a joint analysis confirming sterile neutrino parameters, discusses their cosmological implications, and proposes extending the Standard Model with additional right-handed neutrinos.

Findings

Sterile neutrino parameters confirmed at 5.8σ confidence level.

Sterile neutrinos contribute 5% to cosmic energy density.

Extension with two more heavy sterile neutrinos could explain 27% of dark matter.

Abstract

Joint analysis of the results of the Neutrino-4 experiment and the data of the GALLEX, SAGE and BEST experiments confirms the parameters of neutrino oscillations declared by the Neutrino-4 experiment $(\Delta m_{14}^2= 7.3 \text{eV}^2$ and $\sin^2 2\theta_{14} \approx 0.36)$ and increases the confidence level to $5.8\sigma$. Such a sterile neutrino thermalizes in cosmic plasma, contributes 5% to the energy density of the Universe, and can explain 15-20% of dark matter. It is discussed that the extension of the neutrino model by introducing two more heavy sterile neutrinos in accordance with the number of types of active neutrinos but with very small mixing angles to avoid thermalization will make it possible to explain the large-scale structure of the Universe and bring the contribution of sterile neutrinos to the dark matter of the Universe to the level of 27%. Sterile neutrinos are essentially right-handed neutrinos. The dynamic process of the dark matter generation, consisting of three right-handed neutrinos, is presented. Expansion of the Standard Model by introducing right-handed neutrinos seems possible. The scheme of masses and the scheme of mixing flavors are considered.