Averaging the oscillations of supernova neutrinos
Rasmus Sloth Lundkvist (MPI Heidelberg)

When a heavy star reaches the end of its life, it explodes in a core collapse supernova emitting more than 99% of the released energy as neutrinos. The neutrinos are produced at the centre of the supernova and as they travel through its dense layers, their flavour is changed by an interplay between the background and their vacuum masses. I will explain how we can explicitly describe decoherence effects in such a neutrino gas starting from neutrino wave packets. Afterwards, I will turn to the non-linear effects that arise because the neutrinos themselves are a part of the background. These effects include collective oscillations, but they also cover the recently discovered effects that result from going beyond a spherically symmetric emission model for the supernova neutrinos.