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Title: Light sterile neutrinos in the early universe

Cosmological and terrestrial data suggests the number of light neutrinos may be greater than 3, motivating a careful reexamination of cosmological bounds on extra light species. Big bang nucleosynthesis constrains the number of relativistic neutrino species present during nucleosynthesis, N{sub eff}{sup BBN}, while measurements of the cosmic microwave background (CMB) angular power spectrum constrain the effective energy density in relativistic neutrinos at the time of matter-radiation equality, N{sub eff}{sup CMB}. We review a scenario with two sterile neutrinos and explore whether partial thermalization of the sterile states can ease the tension between cosmological constraints on N{sub eff}{sup BBN} and terrestrial data. We conclude that, still, two additional light sterile neutrinos species cannot fit all the data at the 95% confidence level.
Authors:
 [1]
  1. Department of Physics, Arizona State University, Tempe, Arizona 85287-1404 (United States)
Publication Date:
OSTI Identifier:
22306114
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1604; Journal Issue: 1; Conference: PPC 2013: 7. international conference on interconnections between particle physics and cosmology, Lead-Deadwood, SD (United States), 24 Jun - 6 Jul 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ENERGY DENSITY; LIMITING VALUES; NEUTRINOS; NUCLEOSYNTHESIS; RELATIVISTIC RANGE; RELICT RADIATION; REVIEWS; SPECTRA; THERMALIZATION; UNIVERSE