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Updated: Jun 21, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
Relic density of neutrinos with primordial asymmetries
Sergio Pastor1, Teguayco Pinto, Georg G Raffelt
1Institut de Física Corpuscular (CSIC-Universitat de València), Ed. Instituts d'Investigació, 46071 València, Spain.
Abstract:
We study flavor oscillations in the early Universe, assuming primordial neutrino-antineutrino asymmetries. Including collisions and pair processes in the kinetic equations, we not only estimate the degree of flavor equilibration, but for the first time also kinetic equilibration among neutrinos and with the ambient plasma. Typically, the restrictive big-bang nucleosynthesis bound on the nu_{e}nu[over]_{e} asymmetry indeed applies to all flavors as claimed in the previous literature, but fine-tuned initial asymmetries always allow for a large surviving neutrino excess radiation that may show up in precision cosmological data.
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