Cosmological Neutrino Mass Limit Revisited

Abstract

We consider the equilibration of the 'wrong--helicity' Dirac neutrino states ${\nu }_{+}$ and ${\overline{\nu }}_{-}$ in the early Universe via weak interactions and calculate carefully the thermally averaged production rate, taking into account all the relevant scattering and decay processes. Requiring that the production rate is less than the Hubble parameter at the onset of QCD phase transition so that the nucleosynthesis predictions are not contradicted, we find for $T_{\mathrm{QCD}}\simeq 200$ MeV the upper limits $m_{ν_τ}\lsim 740$ keV and $m_{ν_μ}\lsim 480$ keV.

11 pages (2 figures available on request), NORDITA-92/87 P

Cited by in corpus (11)

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• An improved cosmological bound on the tau-neutrino mass
• Bounds on Dirac Neutrino Masses from Nucleosynthesis
• Lepton Flavor Violation and the Tau Neutrino Mass
• Nucleosynthesis Limits on the Mass of Long Lived Tau and Muon Neutrinos
• Constraints on Massive Tau Neutrinos and their Cosmological Implications
• Neutrinos in Cosmology
• Cosmological abundances of right-handed neutrinos