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arXiv · hep-ph/9910444

Neutrino oscillations in the early universe: How large lepton asymmetry can be generated?

A. D. Dolgov·S. H. Hansen·S. Pastor·D. V. Semikoz
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Abstract

The lepton asymmetry that could be generated in the early universe through oscillations of active to sterile neutrinos is calculated (almost) analytically for small mixing angles, sin 2θ< 10^{-2}. It is shown that for a mass squared difference, δm^2=-1 eV^2 it may rise at most by 6 orders of magnitude from the initial ``normal'' value of 10^{-10}, since the back-reaction from the refraction index terminates this rise while the asymmetry is still small. Only for very large mass differences, δm^2 about 10^9 eV^2, the lepton asymmetry could reach a significant magnitude exceeding 0.1.

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A. D. Dolgov, S. H. Hansen, S. Pastor, D. V. Semikoz. 1999-10-22. Neutrino oscillations in the early universe: How large lepton asymmetry can be generated?. https://doi.org/10.1016/s0927-6505(00)00111-0

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