1996/06/10 by Craig J. Copi, Craig J Copi, David N. Schramm +1 · 2 citations
Mathematics · Physics and Astronomy · #Abundance (ecology) #Astrophysics #Big Bang nucleosynthesis #Biology #Cosmology #Dark Matter and Cosmic Phenomena #Deuterium #Ecology #Imperfect #Limit (mathematics) #Massless particle #Mathematics #Neutrino #Neutrino Physics Research #Nuclear physics #Nucleosynthesis #Particle physics #Particle physics theoretical and experimental studies #Philosophy #Physics #Supernova #astro-ph
paper · pdf · doi:10.1103/physrevd.55.3389
published as Phys.Rev.D55:3389-3393,1997 · 10 pages, 2 figures (LaTeX 2.09 using epsf.sty and rotate.sty)
arxiv created 1996/06/10 · openalex publication_date 1997/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Concern about the systematic uncertainty in the4He abundance as well as the chemical evolution of3He leads us to reexamine this important limit. It is shown that with conservative assumptions no more than the equivalent four massless neutrino species are allowed. Even with the most extreme estimates of the astrophysical uncertainties a meaningful limit still exists, less than five massless neutrino species, and illustrates the robustness of this argument. We show that a definitive measurement of the deuterium abundance in high-redshift hydrogen clouds can sharpen the limit.