Characterizing quasi-steady states of fast neutrino-flavor conversion by stability and conservation laws

Understand

The question of what ingredients characterize the quasi-steady state of fast neutrino-flavor conversion (FFC) is one of the long-standing riddles in neutrino oscillation.

• Addressing this issue is necessary for accurate modeling of neutrino transport in core-collapse supernova and binary neutron star merger.
• Recent numerical simulations of FFC have shown, however, that the quasi-steady state is sensitively dependent on boundary conditions in space, and the physical reason for the dependence is not clear at present.
• In this study, we provide a physical interpretation of this issue based on arguments with stability and conservation laws.