2021/10/21 by Julien Froustey
Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmology and Gravitation Theories #Decoupling (probability) #Electron #Electron neutrino #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nuclear physics #Particle physics #Physics #Theoretical physics #Universe #astro-ph.CO #hep-ph
paper · pdf · doi:10.1088/1742-6596/2156/1/012013
5 pages, 2 figures. Based on arXiv:2008.01074. Proceedings for the 17th International Conference on Topics in Astroparticle and Underground Physics (TAUP2021)
arxiv created 2021/10/21 · openalex publication_date 2021/12/01 · arxiv updated 2022/03/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In the primordial Universe, neutrino decoupling occurs only slightly before electron-positron annihilations. This leads notably to an increased neutrino energy density compared to the standard instantaneous decoupling approximation, parametrized by the effective number of neutrino species N\rm eff. A precise calculation of neutrino evolution is needed to assess its consequences during the later cosmological stages, and requires to take into account multiple effects such as neutrino oscillations, which represents a genuine numerical challenge. Recently, several key improvements have allowed such a precise numerical calculation, leading to the new reference value N\rm eff=3.0440.