Sep 8 – 14, 2019
Toyama International Conference Center
Japan timezone

Active-sterile neutrino oscillations in the early Universe with the complete mixing matrix

Sep 11, 2019, 5:00 PM
206 (Toyama International Conference Center)


Toyama International Conference Center
Oral presentation in parallel session Cosmology Cosmology #2


Dr Sergio Pastor (IFIC (CSIC-Univ Valencia))


In the framework of a 3+1 scheme, we consider the thermalisation of sterile neutrinos in the early Universe taking into account the full 4x4 mixing matrix. The evolution of the neutrino energy distributions is found solving the momentum-dependent kinetic equations with full collision terms, as in our previous analyses of flavour neutrino decoupling in the standard case. The degree of thermalisation of the sterile state is shown in terms of the effective number of neutrinos ($N_{\rm eff}$) and its dependence on the three additional mixing angles ($\theta_{14}$, $\theta_{24}$ and $\theta_{34}$) is discussed. Our results are relevant for fixing the contribution of a fourth light neutrino species to the cosmological energy density, whose value is very restricted by the final Planck analysis.

Primary author

Dr Sergio Pastor (IFIC (CSIC-Univ Valencia))


Dr Pablo Fernández de Salas (OKC (Stockholm University)) Dr Stefano Gariazzo (IFIC - CSIC/U. Valencia)

Presentation materials