Analytical treatment of neutrino asymmetry equilibration from flavor oscillations in the early universe

By Y. Wong. 2002

175 citations recorded by the source corpus.

A recent numerical study by A. D. Dolgov, S. H. Hansen, S. Pastor, S. T. Petcov, G. G. Raffelt, and D. V. Semikoz (DHPPRS) [Nucl. Phys. B632, 363 (2002)] found that complete or partial equilibrium between all active neutrino flavors can be achieved before the big bang nucleosynthesis epoch via flavor oscillations, if the oscillation parameters are those inferred from the atmospheric and solar neutrino data, and, in some cases, if ${\ensuremath{\theta}}_{13}$ is also sizable. As such, cosmological constraints on the electron neutrino-antineutrino asymmetry are now applicable in all three neutrino sectors. In the present work, we provide an analytical treatment of the scenarios considered in DHPPRS, and demonstrate that their results are stable even for very large initial asymmetries. The equilibration mechanism can be understood in terms of a Mikheyev-Smirnov-Wolfenstein-like effect for a maximally mixed and effectively monochromatic system. We also comment on the DHPPRS's choices of mixing parameters, and their handling of collisional effects, both of which could impinge on the extent of flavor equilibrium.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d826c093c25164754279949397b8e895e4dcba5b

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In Nuclear and High Energy Physics

1. M. Drewes
2. S. Hannestad
3. I. Tamborra
4. Y. Wong
5. T. Tram
6. G. Raffelt
7. E. Vangioni
8. Jean-Philippe Uzan

Citations in the corpus

• Self-induced conversion in dense neutrino gases: Pendulum in flavour space (2006, background): “Various qualitative and quantitative aspects of synchronised oscillations and applications to neutrino flavour oscillations in the early universe [18, 19, 20, 21] were studied a few years ago, motivated by the question if neutrinos with chemical potentials reach flavour equilibrium in the early univ”
• The Phenomenology of Right Handed Neutrinos (2013, background): “to make the asymmetries in individual flavours equal43 [257–259].”
• Thermalisation of light sterile neutrinos in the early universe (2012, background): “few×10−2 [34–39] and while no exact bound has been derived in models with sterile neutrinos, we expect that the upper bound is of the same order of magnitude.”
• Precision big bang nucleosynthesis with improved Helium-4 predictions (2018, background): “(159) The neutrino oscillations imply that the various flavors must reach an equilibrium for which the chemical potentials are equal (Dolgov et al., 2002; Wong, 2002).”
• Self-induced conversion in dense neutrino gases : Pendulum in flavor space (2006, unknown): “Various qualitative and quantitative aspects of synchronised oscillations and applications to neutrino flavour oscillations in the early universe [18, 19, 20 , 21] were studied a few years ago, motivated by the question if neutrinos with chemical potentials reach flavour equilibrium in the early un”