Fermi-Boltzmann statistics of neutrinos and relativistic effective degrees of freedom

Abstract

We investigate the effect of the presence of non-pure fermionic neutrinos on the relativistic effective degrees of freedom in the early universe. The statistics of neutrinos is transformed continuously from Fermi-Dirac to Maxwell-Boltzmann statistics. We find that the relativistic degrees of freedom decreases with the deviation from pure Fermi-Dirac statistics of neutrinos if there are constant and large lepton asymmetries. Additionally, we confirm that the change of the statistics of neutrinos from Fermi-Dirac to Maxwell-Boltzmann is not sufficient to cover the excess of the effective number of neutrinos.

15 pages, 5 figures, version to appear in Modern Physics Letters A

References in corpus (2)

• Relic Neutrinos, thermal axions and cosmology in early 2014
• Big-Bang Nucleosynthesis in comparison with observed helium and deuterium abundances - possibility of a non-standard model

Cited by in corpus (2)

• What can CMB observations tell us about the neutrino distribution function?
• Probing Beyond the Standard Model Physics with Double-beta Decays