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Relic Neutrino Decoupling Including Flavour Oscillations

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	Mangano, Gianpiero; Miele, Gennaro; Pastor Carpi, Sergio; Pinto, Teguayco; Pisanti, Ofelia; Serpico, Pasquale D.
	This document is a artículoDate2005
	Este documento está disponible también en : http://hdl.handle.net/10550/37350
	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 Neff=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.
	Mangano, Gianpiero Miele, Gennaro Pastor Carpi, Sergio Pinto, Teguayco Pisanti, Ofelia Serpico, Pasquale D. 2005 Relic Neutrino Decoupling Including Flavour Oscillations Nuclear Physics B 729 221 234
	http://dx.doi.org/10.1016/j.nuclphysb.2005.09.041