TY  - JOUR
AU  - Gariazzo, S.
AU  - de Salas, P. F.
AU  - Pastor, S.
PY  - 2019
DA  - 2019//
TI  - Thermalisation of sterile neutrinos in the early universe in the 3+1 scheme with full mixing matrix
T2  - J. Cosmol. Astropart. Phys.
JO  - Journal of Cosmology and Astroparticle Physics
SP  - 014
EP  - 30pp
VL  - 07
IS  - 7
PB  - Iop Publishing Ltd
KW  - cosmological neutrinos
KW  - neutrino properties
KW  - particle physics – cosmology connection
KW  - physics of the early universe
AB  - In the framework of a 3+1 scheme with an additional inert state, we consider the thermalisation of sterile neutrinos in the early Universe taking into account the full 4 x 4 mixing matrix. The evolution of the neutrino energy distributions is found solving the momentum-dependent kinetic equations with full diagonal collision terms, as in 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-eff, and its dependence on the three additional mixing angles (theta(14), theta(24), theta(34)) and on the squared mass difference Delta m(41)(2) 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 well constrained by the final Planck analysis. For the preferred region of active-sterile mixing parameters from short-baseline neutrino experiments, we find that the fourth state is fully thermalised (N-eff similar or equal to 4).
SN  - 1475-7516
UR  - https://arxiv.org/abs/1905.11290
UR  - https://doi.org/10.1088/1475-7516/2019/07/014
DO  - 10.1088/1475-7516/2019/07/014
LA  - English
N1  - WOS:000474782100001
ID  - Gariazzo_etal2019
ER  -