Single-wave solutions of the neutrino fast flavor system. Part I. Mechanical properties
arXiv:2601.15372 · doi:10.1007/JHEP06(2026)111
Abstract
A dense neutrino plasma can exhibit collective flavor evolution caused by neutrino--neutrino refraction. Recently, a new class of exact nonlinear inhomogeneous solutions was discovered: single-wave (SW) solutions of the fast flavor system. The key property is that the flavor occupation numbers remain homogeneous, whereas the field of flavor coherence varies spatially with a single wave vector. The equations of motion for this structure resemble those of a collection of classical spins, in analogy with the homogeneous slow and fast flavor cases. In contrast, the SW system is not integrable (it does not possess Gaudin invariants) so that, while two-beam pendulum solutions are inevitable, they do not extend to a multi-angle system. We develop a taxonomy of all known nonlinear collective flavor solutions, explaining the overlap between categories and their differences.
Minor comments added, updated to the published version: 24 pages, 1 figure
References in corpus (23)
- Simulation of Coherent Non-Linear Neutrino Flavor Transformation in the Supernova Environment I: Correlated Neutrino Trajectories
- Collective neutrino flavor transitions in supernovae and the role of trajectory averaging
- Multiple Spectral Splits of Supernova Neutrinos
- Fast Pairwise Conversion of Supernova Neutrinos: A Dispersion-Relation Approach
- New Developments in Flavor Evolution of a Dense Neutrino Gas
- Coherent Development of Neutrino Flavor in the Supernova Environment
- The multi-angle instability in dense neutrino systems
- Analysis of Collective Neutrino Flavor Transformation in Supernovae
- Adiabaticity and spectral splits in collective neutrino transformations
- Neutrino oscillations in supernovae: angular moments and fast instabilities
- Self-induced decoherence in dense neutrino gases
- Fast neutrino flavor instability and neutrino flavor lepton number crossings
- Neutrino Flavor Pendulum Reloaded: The Case of Fast Pairwise Conversion
- Damping the neutrino flavor pendulum by breaking homogeneity
- Slow and fast collective neutrino oscillations: Invariants and reciprocity
- Flavor solitons in dense neutrino gases
- Neutrino Oscillations in Core-Collapse Supernovae and Neutron Star Mergers
- Fast flavor conversions at the edge of instability in a two-beam model
- Flavor isospin waves in one-dimensional axisymmetric neutrino gases
- Theory of neutrino slow flavor evolution. Part I. Homogeneous medium
- Fast Flavor Pendulum: Instability Condition
- Collective flavor conversions are interactions of neutrinos with quantized flavor waves
- Thermodynamics of oscillating neutrinos