Hiding relativistic degrees of freedom in the early universe

V. Barger, James P. Kneller, Paul Langacker, Danny Marfatia, Gary Steigman

Research output: Contribution to journalArticlepeer-review

86 Scopus citations


We quantify the extent to which extra relativistic energy density can be concealed by a neutrino asymmetry without conflicting with the baryon asymmetry measured by the Wilkinson Microwave Anisotropy Probe (WMAP). In the presence of a large electron neutrino asymmetry, slightly more than seven effective neutrinos are allowed by Big Bang Nucleosynthesis (BBN) and WMAP at 2σ. The same electron neutrino degeneracy that reconciles the BBN prediction for the primordial helium abundance with the observationally inferred value also reconciles the LSND neutrino with BBN by suppressing its thermalization prior to BBN.

Original languageEnglish (US)
Pages (from-to)123-128
Number of pages6
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number3-4
StatePublished - Sep 11 2003

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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