Dynamical equilibria of fast neutrino flavor conversion

Abstract: Dense neutrino systems, which display collectivity mediated by the weak interaction, have deep parallels with mean-field kinetic systems governed by other fundamental forces. We identify analogues in fast flavor conversion (FFC) of some time-honored nonlinear phenomena in plasmas and self-gravitating systems. We focus in particular on nonlinear Landau damping and collisionless equilibria, which are likely important pieces of the unsolved puzzle of neutrino oscillations in core-collapse supernovae and neutron star mergers. Our analysis additionally reveals the previously unexplored phenomenon of flavor-wave synchronization.