Large neutrino asymmetries from neutrino oscillations
R. Foot, M. J. Thomson, R. R. Volkas
TL;DR
Contrary to previous studies, it is shown that large neutrino asymmetries can arise due to oscillations between ordinary neutrinos and sterile neutRinos, which means that the big bang nucleosynthesis (BBN) bounds on the mass and mixing of ordinaryNeutrinos with sterile neut rinos can be evaded.
Abstract
We re-examine neutrino oscillations in the early universe. Contrary to previous studies, we show that large neutrino asymmetries can arise due to oscillations between ordinary neutrinos and sterile neutrinos. This means that the Big Bang Nucleosynthesis (BBN) bounds on the mass and mixing of ordinary neutrinos with sterile neutrinos can be evaded. Also, it is possible that the neutrino asymmetries can be large (i.e. $\stackrel{>}{\sim} 10\%$), and hence have a significant effect on BBN through nuclear reaction rates.