2006/07/31 by Gianpiero Mangano, G. Mangano, Gennaro Miele +7 · 2 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Cosmic neutrino background #Decoupling (probability) #Electron #Electron neutrino #Measurements of neutrino speed #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Solar neutrino #Sterile neutrino #astro-ph #hep-ph
paper · pdf · doi:10.1016/j.nuclphysb.2006.09.002
published as Nucl.Phys. B756 (2006) 100-116 · 23 pages, 5 figures. To be published in NPB
arxiv created 2006/09/01 · openalex publication_date 2006/09/23 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino-electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species (Neff) and the impact on the abundance of He-4 produced during Big Bang Nucleosynthesis. We find that, for NSI parameters within the ranges allowed by present laboratory data, non-standard neutrino-electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass. Nonetheless, the presence of neutrino-electron NSI may enhance the entropy transfer from electron-positron pairs into neutrinos instead of photons, up to a value of Neff=3.12. This is almost three times the correction to Neff=3 that appears for standard weak interactions.