1999/04/03 by Kevork N. Abazajian, Kevork Abazajian, X.R. Shi +5
Physics and Astronomy · #Astrophysics (astro-ph) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Neutrino Physics Research #Quantum, superfluid, helium dynamics #astro-ph #hep-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9904052
6 pages, Latex, proceedings for Division of Particles and Fields Conference, University of California, Los Angeles, January 5-9, 1999
arxiv created 1999/04/03 · openalex publication_date 1999/04/03 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate the effects of matter-enhanced (MSW) transformation of\nneutrinos in the Early Universe on the primordial helium yield (Yp). We find\nthat Yp is affected much more by the MSW-induced alterations in the neutrino\nenergy spectra than by the associated change in expansion rate. Specifically,\nthe absence due to transformation of low energy electron neutrinos can\nsignificantly affect neutron-proton weak interconversion rates through the\nlifting of Fermi-blocking of neutron decay at low energies and through halting\nlow-energy neutrino capture on neutrons. We find that the change of Yp within\na causal horizon is -0.005\≤ \δ Yp \≤ 0.013 for m_\ν\μ,\τ2 -\nm\νs2 \≤ 104 eV2 in the case of \ν\μ,\τ-\νs-\νe mixing,\nwith the lower limit at m_\ν\μ,\τ2 - m\νs2 \≈ 100 eV2,\nand -0.002\≤ \δ Yp \≤ 0.020 for m\νe2 - m\νs2 \≤ 1 eV2 in\nthe case of \νe-\νs mixing.\n