N-mode coherence in collective neutrino oscillations

Understand

We study two-flavor neutrino oscillations in a homogeneous and isotropic ensemble under the influence of neutrino-neutrino interactions.

• For any density there exist forms of collective oscillations that show self-maintained coherence.
• They can be classified by a number N of linearly independent functions that describe all neutrino modes as linear superpositions.
• What is more, the dynamics is equivalent to another ensemble with the same effective density, consisting of N modes with discrete energies E_i with i=1, ..., N.