2014/09/30 by Jun Iizuka, Teruyuki Kitabayashi
Physics and Astronomy · #Cosmology and Gravitation Theories #Cover (algebra) #Degrees of freedom (physics and chemistry) #Lepton #Lepton number #Neutrino #Neutrino Physics Research #Noncommutative and Quantum Gravity Theories #Standard Model (mathematical formulation) #Universe #hep-ph
paper · pdf · doi:10.1142/s0217732315500030
published as Mod. Phys. Lett. A, Vol. 30, No. 1 (2015) 1550003 · 15 pages, 5 figures, version to appear in Modern Physics Letters A
arxiv created 2014/11/22 · openalex publication_date 2015/01/02 · arxiv updated 2015/01/07 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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.