Nonequilibrium Neutrino Oscillations and Primordial Production of He-4

Abstract

We studied nonequilibrium oscillations between left-handed electron neutrinos and nonthermalized sterile neutrinos in medium for resonant and nonresonant cases. The exact kinetic equations for neutrinos, written in terms of neutrino density matrix in {\it momentum space} were analyzed. The evolution of neutrino density matrix was numerically calculated. This allowed to study precisely the evolution of the neutrino number densities, energy spectrum distortion and the asymmetry between neutrinos and antineutrinos for each momentum mode. The influence of nonequilibrium oscillations on the primordial production of He-4 was calculated. Cosmological constraints on the oscillation parameters were obtained.

LaTeX, 7 pages, 6 Postscript figures, figures are included in the revised text (epsf.sty)

References in corpus (4)

• Neutrino decoupling in the early Universe
• Large neutrino asymmetries from neutrino oscillations
• Chaotic Amplification of Neutrino Chemical Potentials by Neutrino Oscillations in Big Bang Nucleosynthesis
• Neutrino Oscillations in the Early Universe with Nonequilibrium Neutrino Distributions

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