Speaker
Description
In the seesaw type-I mechanism neutrinos get masses and mixing due to Yukawa coupling to the Higgs boson and sterile neutrinos -- Majorana fermions singlet with respect to the Standard Model gauge group. Sterile neutrinos of mass in keV range is a natural candidate for dark matter being produced in the early Universe by mixing with the active neutrinos originated from the Yukawa coupling after electroweak transition. Here we consider the model with additional scalar field coupled to the sterile neutrino and capable of changing its effective mass while the Universe expands. This can drastically change the sterile neutrino production, making relatively high sterile-neutrino mixing cosmologically allowed, suggesting new mechanism to produce cold dark matter sterile neutrinos, etc, depending on the dynamics of the scalar sector.
