Collective fast neutrino flavor conversions in a 1D box: Initial condition and long-term evolution

Understand

We perform numerical simulations of fast collective neutrino flavor conversions in an one-dimensional box mimicking a system with the periodic boundary condition in one spatial direction and translation symmetry in the other two dimensions.

• We evolve the system over several thousands of the characteristic timescale (inverse of the interaction strength) with different initial $\bar\nu_e$ to $\nu_e$ number density ratios and different initial seed perturbations.
• We find that small scale structures are formed due to the interaction of the flavor waves.
• This results in nearly flavor depolarization in a certain neutrino phase space, when averaged over the entire box.