Synchronization vs. decoherence of neutrino oscillations at intermediate densities

Understand

We study collective oscillations of a two-flavor neutrino system with arbitrary but fixed density.

• In the vacuum limit, modes with different energies quickly de-phase (kinematical decoherence), whereas in the limit of infinite density they lock to each other (synchronization).
• For intermediate densities, we find different classes of solutions.
• There is always a phase transition in the sense of partial synchronization occurring only above a density threshold.