Cosmological bounds on active-sterile neutrino mixing after Planck data

Topical Research Meeting: Prospects in Neutrino Physics

Saviano, Ninetta^1

Institute for Particle Physics Phenomenology, Department of Physics, Durham University, Durham

DH1 3LE, United Kingdom^1

关键词: Early universe;    Energy density;    Extra radiation;    Mixing parameters;    Neutrino mass;    Parameter spaces;    Planck satellites;    Sterile neutrinos;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/598/1/012029/pdf
DOI  :  10.1088/1742-6596/598/1/012029

来源: IOP

【 摘 要 】

Light sterile neutrinos can be produced by oscillations with active neutrinos in the early universe. Their properties can be constrained by their contribution as extra-radiation, parametrized in terms of the effective number of neutrino species Neff, and to the universe energy density today Ωvh2. Both these parameters have been measured to quite a good precision by the Planck satellite experiment. We use these results to update the bounds on the parameter space of (3+1) sterile neutrino scenarios, with an active-sterile neutrino mass squared splitting in the range (10-5- 102)eV2. For the first time we take into account the possibility of two non-vanishing active-sterile mixing angles. We find that the mass and mixing parameter space is severely constrained. In particular sterile neutrinos with m ∼ O(1) eV are strongly disfavoured by neutrino mass bound.