http://arxiv.org/abs/2210.09218
We investigate the collision-induced flavor instability in homogeneous, isotropic, dense neutrino gases in the two-flavor mixing scenario with energy-dependent scattering. We find that the growth rate of such an instability, if it exists, is the negative average of the flavor-decohering collision rates of the neutrinos weighted by the electron lepton number distribution of the neutrinos. This growth rate is independent of the neutrino mass-splitting, the matter density, and the neutrino density, although the initial amplitude of the unstable oscillation mode can be suppressed by a large matter density. Our results suggest that neutrinos are likely to experience collision-induced flavor conversions deep inside a core-collapse supernova even when both the fast and slow collective flavor oscillations are suppressed. However, this phenomenon may not occur in a neutron star merger because the electron antineutrinos have a larger average energy and more abundance than the electron neutrinos in such an environment.
Y. Lin and H. Duan
Tue, 18 Oct 22
87/99
Comments: 6 pages, 4 figures