Sterile Neutrinos in the Early Universe
We discuss the role played by right-handed sterile neutrinos in the early universe. We show how the well known 4He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right-handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented.
KeywordsSterile Neutrino Lawrence Livermore National Laboratory Dirac Neutrino Neutrino Magnetic Moment Neutrino Flavor
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