Relic neutrino decoupling including flavour oscillations
Abstract
In the early universe, neutrinos are slightly coupled when electron-positron pairs annihilate transferring their entropy to photons. This process originates non-thermal distortions on the neutrino spectra which depend on neutrino flavour, larger for nu_e than for nu_mu or nu_tau. We study the effect of three-neutrino flavour oscillations on the process of neutrino decoupling by solving the momentum-dependent kinetic equations for the neutrino spectra. We find that oscillations do not essentially modify the total change in the neutrino energy density, giving N_eff=3.046 in terms of the effective number of neutrinos, while the small effect over the production of primordial 4He is increased by O(20%), up to 2.1 x 10^{-4}. These results are stable within the presently favoured region of neutrino mixing parameters.
Cite
@article{arxiv.hep-ph/0506164,
title = {Relic neutrino decoupling including flavour oscillations},
author = {Gianpiero Mangano and Gennaro Miele and Sergio Pastor and Teguayco Pinto and Ofelia Pisanti and Pasquale D. Serpico},
journal= {arXiv preprint arXiv:hep-ph/0506164},
year = {2009}
}
Comments
18 pages, 2 figures