Flavomon ray tracing in matter gradients

Flavor instabilities develop in neutrino plasmas through emission of flavomons, the quanta of flavor waves. We derive the flavomon equations of motion in slowly varying environments, notably the matter gradients of supernovae, and use them to construct a flavomon ray tracing framework. Combined with a quasi-linear description of flavomon growth, we thus develop a new approach to the global evolution of flavor instabilities. As a first application, we show that the growth of neutrino-mass-induced instabilities is slowed down, but not suppressed, by the inevitable matter gradients. Local stability analysis alone cannot gauge the impact of inhomogeneities and instead must be coupled to flavomon ray tracing.