Constraints on almost-Dirac neutrinos from neutrino-antineutrino oscillations

Journal Article · Mon May 25 04:00:00 EDT 1992 · Physical Review Letters; (United States)

DOI:https://doi.org/10.1103/PhysRevLett.68.3137· OSTI ID:7286960

Cline, J M ^[1]

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1. Department of Physics, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)

If a neutrino has both Dirac and Majorana masses ({ital m},{mu}), as some recent models predict, {nu}{leftrightarrow}{bar {nu}} oscillations within a single generation may cause a violation of the nucleosynthesis bound on the number of light neutrino species. Taking into account the effects of finite temperature and density, we find that {mu}{ital m} must be less than 3{times}10{sup {minus}5} eV{sup 2}, which is too small to explain atmospheric neutrino observations. The bound can be softened to 0.05 eV{sup 2} if the right-handed components couple to massless bosons (Majorons). We introduce a simple but quantitatively accurate formalism for tracking the approach of the sterile state to thermal equilibrium.

• OSTI ID: 7286960
• Journal Information: Physical Review Letters; (United States), Journal Name: Physical Review Letters; (United States) Vol. 68:21; ISSN PRLTA; ISSN 0031-9007
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
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DIFFERENTIAL EQUATIONS
ELEMENTARY PARTICLES
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FERMIONS
GOLDSTONE BOSONS
LEPTONS
LIMITING VALUES
MASS
MASSLESS PARTICLES
MATHEMATICAL MODELS
NEUTRINO OSCILLATION
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STANDARD MODEL
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