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Impact of massive tau-neutrinos on primordial nucleosynthesis. Exact calculations

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

The influence of a massive Majorana tau-neutrino on primordial nucleosynthesis is rigorously calculated. The system of three integro-differential kinetic equations is solved numerically for the tau-neutrino mass in the interval from 0 to 20 MeV. It is found that the usual assumption of kinetic equilibrium is strongly violated and non-equilibrium corrections considerably amplify the effect. Even a very weak restriction from nucleosynthesis, allowing for one extra massless neutrino species, permits to conclude that m_ν_τ< 1 MeV. For a stricter bound, e.g. for dN < 0.3, the limit is m_ν_τ< 0.35 MeV.

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A. D. Dolgov, S. H. Hansen, D. V. Semikoz. 1999-02-28. Impact of massive tau-neutrinos on primordial nucleosynthesis. Exact calculations. https://doi.org/10.1016/s0550-3213(98)00307-1

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