## Abstract

We compute the nucleosynthesis bounds on the masses of stable Dirac and Majorana neutrinos by solving an evolution equation network comprising of all neutrino species which in the Dirac case includes different helicity states as separate species. We will not commit ourselves to any particular value of the nucleosynthesis bound on the effective number of light neutrino degrees of freedom N_{v}, but present all our mass bounds as functions of ΔN_{v}. For example, we find that the excluded region in the mass of a Majorana μ- or τ-neutrino, 0.29 MeV < m^{M}_{v} < 53 MeV corresponding to a bound ΔN_{v} < 0.3 gets relaxed to 0.95 MeV < m^{M}_{v} < 32 MeV if ΔN_{v} < 1.0 is used instead. For the Dirac neutrinos ΔN_{v} < 1.0 gives the upper limits (for T_{QCD} = 100 MeV) m^{D}_{vμ} < 0.31 MeV and m^{D}_{v-} < 0.37 MeV and the lower limit m^{D}_{v} > 25 MeV. Together with the present experimental limit nucleosynthesis excludes m^{M}_{vτ} > 0.95 MeV and m^{D}_{vτ} > 0.37 MeV at 95% CL.

Original language | English (US) |
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Pages (from-to) | 169-185 |

Number of pages | 17 |

Journal | Astroparticle Physics |

Volume | 6 |

Issue number | 2 |

DOIs | |

State | Published - Feb 1997 |

Externally published | Yes |

## ASJC Scopus subject areas

- Astronomy and Astrophysics