Nonequilibrium Neutrino Oscillations in the Early Universe with an   Inverted Neutrino-Mass Hierarchy
  The annihilation of electron-positron pairs around one second after the big bang distorts the Fermi-Dirac spectrum of neutrino energies. We determine the distortions assuming neutrino mixing with an inverted neutrino-mass hierarchy. Nonequilibrium thermodynamics, the Boltzmann equation, and numerical integration are used to achieve the results. The various types of neutrino behavior are established as a function of masses and mixing angles. 
V. Alan Kostelecky (Indiana U.) Stuart Samuel (CCNY)