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Cosmological abundances of right-handed Dirac neutrinos

Kari Enqvist
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Abstract

The equilibration of the right-helicity states $ν_+$ of light Dirac-neutrinos is discussed. I point out that the $ν_+$ production rate is enhanced by weak gauge boson pole effects so that the right-helicity component of $ν_τ$ is brought into equilibrium at $T\simeq 10$ GeV independently of the initial abundance, provided $m_{ν_τ}\gsim 10$ keV. Neutrino spin flip in primordial magnetic fields and the resulting bound on $μ_ν$ is also discussed.

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Kari Enqvist. 1996-09-25. Cosmological abundances of right-handed Dirac neutrinos. https://arxiv.org/abs/hep-ph/9609464

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