Fast Flavor Depolarization of Supernova Neutrinos

Understand

Flavor-dependent neutrino emission is critical to the evolution of a supernova and its neutrino signal.

• In the dense anisotropic interior of the star, neutrino-neutrino forward-scattering can lead to fast collective neutrino oscillations, which has striking consequences.
• We present a theory of fast flavor depolarization, explaining how neutrino flavor differences become smaller, i.e., depolarize, due to diffusion to smaller angular scales.
• We show that transverse relaxation determines the epoch of this irreversible depolarization.