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Open Access Publications from the University of California

A primordial 4He constraint on Dirac neutrino masses

  • Author(s): Fuller, George M
  • Malaney, Robert A
  • et al.

The implications of the Z0-width experiment for the number of neutrino flavors taken together with the4He constraint on the energy density at the nucleosynthesis epoch, can give a limit on the extent to which a right-handed neutrino sea could contribute to the expansion rate of the universe during Big Bang nucleosynthesis. Since the population of the right-handed neutrino sea depends on the neutrino mass we can extract a Dirac neutrino mass limit of mv≪ 150 keV. This limit could apply to νμor ντif they have purely Dirac masses. © 1991.

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