Creation of large spatial fluctuations in neutrino asymmetry by neutrino oscillations

Abstract

We consider active-sterile neutrino oscillations in the early universe in an inhomogeneous isocurvature background. We show that very small initial baryonic seed-inhomogeneities can trigger a growth of very large amplitude spatial fluctuations in lepton asymmetry. Domains of varying asymmetry are observed to persist for a long time despite dissipative effects. The space dependent asymmetry profiles give rise to MSW-resonances within the domain boundaries, enhancing dramatically the equilibration of the sterile neutrino species. According to our one-dimensional toy-model, the effect is so strong that almost the entire parameter space where exponential growth of asymmetry occurs would be ruled out by nucleosynthesis.

1+21 pages, 3 figures

Cited by in corpus (5)

• BBN bounds on active-sterile neutrino mixing
• Telling Three from Four Neutrinos with Cosmology
• Neutrino Propagation in Dense Astrophysical Systems
• Big Bang nucleosynthesis, matter-antimatter regions, extra relativistic species, and relic gravitational waves
• Oscillation Induced Neutrino Asymmetry Growth in the Early Universe