Many-body effects of collective neutrino oscillations

Collective neutrino oscillations are critical to determine the neutrino flavor content, which has striking impacts on core-collapse supernovae or compact binary merger remnants. It is a challenging many-body problem that so far has been mainly studied at the mean-field approximation. We use a setup that captures the relevant physics and allows exact solution for a large number of neutrinos. We find that quantitative deviation from the mean-field evolution can exist even for a large system. The underlying mechanism due to many-body decoherence in flavor space is analyzed, and similar features have been observed in a spin-1 Bose-Einstein condensate. Our results call for more careful examinations on the possible many-body corrections to collective neutrino oscillations in astrophysical environments.