Cosmological Neutrino Mass Limit Revisited

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....

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Bibliographic Details
Published inarXiv.org
Main Authors Enqvist, K, Uibo, H
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 25.11.1992
Subjects
Decay rate
Helicity
Neutrinos
Nuclear fusion
Phase transitions
Universe
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Summary: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 \(T_{\rm{QCD}}\simeq 200\) MeV the upper limits \(m_{\nu_\tau}\lsim 740\) keV and \(m_{\nu_\mu}\lsim 480\) keV.
ISSN:2331-8422
DOI:10.48550/arxiv.9211307