Collective neutrino flavor oscillations in supernovae from a many body perspective (E. Rrapaj)

Presented by Ermal Rrapaj from the University of Minnesota

Abstract: I study the flavor evolution of a dense neutrino gas by considering vacuum contributions, mat-ter effects and neutrino self-interactions. Assuming a system of two flavors in a uniform matter background, the time evolution of the many-body system in discretized momentum space is com-puted. The multi-angle neutrino-neutrino interactions are treated exactly and compared to both the single-angle approximation and mean field calculations.  I study various configurations of up to twenty neutrinos.

When both flavors are initially present, I find collective oscillations and flavor equilibration develop in the many body treatment but not in the mean field method. This difference persists in dense matter with tiny mixing angle and it can be ascribed to non-negligible flavor polarization
correlations being present. Entanglement entropy is significant in all such cases.