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.

arXiv comment15 pages, 5 figures, version to appear in Modern Physics Letters A

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Cited by in corpus (5)

• What can CMB observations tell us about the neutrino distribution function?
• Probing Beyond the Standard Model Physics with Double-beta Decays
• Cosmological bounds on neutrino statistics
• Asymmetric dark matter and effective number of neutrinos
• Relativistic effective degrees of freedom and quantum statistics of neutrinos