Fast Neutrino Flavor Conversion at Late Time

Abstract

We study the fully nonlinear fast flavor evolution of neutrinos in 1+1 dimensions. Our numerical analysis shows that at late time the system reaches an approximately steady state. Using the steady state approximation we analytically show that the spatial variation of the polarization vectors is given by their precession around a common axis, which itself has a motion reminiscent of a gyroscopic pendulum. We then show that the steady state solution to the equations of motion cannot be separated in position and velocity, that is the motion is not collective in the usual sense. However, the fast evolution allows spectral-swap-like dynamics leading to partial decoherence over a range of velocities, constrained by conservation of lepton number(s). Finally, we numerically show that at late time the transverse components of the polarization vectors become randomly oriented at different spatial locations for any velocity mode and lepton asymmetry.

15 pages, 9 figures

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Cited by in corpus (6)

• Fast flavor oscillations in dense neutrino media with collisions
• On the characteristics of fast neutrino flavor instabilities in three-dimensional core-collapse supernova models
• Collective fast neutrino flavor conversions in a 1D box: Initial condition and long-term evolution
• Neutrino Flavor Conversions in High-Density Astrophysical and Cosmological Environments
• The Fast Flavor Instability in Hypermassive Neutron Star Disk Outflows
• Collisional instabilities of neutrinos and their interplay with fast flavor conversion in compact objects