Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability
Abstract In dense neutrino environments, such as provided by core-collapse supernovae or neutron-star mergers, neutrino angular distributions may be unstable to collective flavor conversions, whose outcome remains to be fully understood. These conversions are much faster than hydrodynamical scales,...
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| Format: | Article |
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SpringerOpen
2024-12-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP12(2024)205 |
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| author | Damiano F. G. Fiorillo Georg G. Raffelt |
| author_facet | Damiano F. G. Fiorillo Georg G. Raffelt |
| author_sort | Damiano F. G. Fiorillo |
| collection | DOAJ |
| description | Abstract In dense neutrino environments, such as provided by core-collapse supernovae or neutron-star mergers, neutrino angular distributions may be unstable to collective flavor conversions, whose outcome remains to be fully understood. These conversions are much faster than hydrodynamical scales, suggesting that self-consistent configurations may never be strongly unstable. With this motivation in mind, we study weakly unstable modes, i.e., those with small growth rates. We show that our newly developed dispersion relation (Paper I of this series) allows for an expansion in powers of the small growth rate. For weakly unstable distributions, we show that the unstable modes must either move with subluminal phase velocity, or very close to the speed of light. The instability is fed from neutrinos moving resonantly with the waves, allowing us to derive explicit expressions for the growth rate. For axisymmetric distributions, often assumed in the literature, numerical examples show the accuracy of these expressions. We also note that for the often-studied one-dimensional systems one should not forget the axial-symmetry-breaking modes, and we provide explicit expressions for the range of wavenumbers that exhibit instabilities. |
| format | Article |
| id | doaj-art-e7d2b6910ae94490937c0596aae140eb |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-e7d2b6910ae94490937c0596aae140eb2025-01-05T12:06:42ZengSpringerOpenJournal of High Energy Physics1029-84792024-12-0120241212810.1007/JHEP12(2024)205Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instabilityDamiano F. G. Fiorillo0Georg G. Raffelt1Deutsches Elektronen-Synchrotron DESYMax-Planck-Institut für PhysikAbstract In dense neutrino environments, such as provided by core-collapse supernovae or neutron-star mergers, neutrino angular distributions may be unstable to collective flavor conversions, whose outcome remains to be fully understood. These conversions are much faster than hydrodynamical scales, suggesting that self-consistent configurations may never be strongly unstable. With this motivation in mind, we study weakly unstable modes, i.e., those with small growth rates. We show that our newly developed dispersion relation (Paper I of this series) allows for an expansion in powers of the small growth rate. For weakly unstable distributions, we show that the unstable modes must either move with subluminal phase velocity, or very close to the speed of light. The instability is fed from neutrinos moving resonantly with the waves, allowing us to derive explicit expressions for the growth rate. For axisymmetric distributions, often assumed in the literature, numerical examples show the accuracy of these expressions. We also note that for the often-studied one-dimensional systems one should not forget the axial-symmetry-breaking modes, and we provide explicit expressions for the range of wavenumbers that exhibit instabilities.https://doi.org/10.1007/JHEP12(2024)205Neutrino InteractionsNeutrino Mixing |
| spellingShingle | Damiano F. G. Fiorillo Georg G. Raffelt Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability Journal of High Energy Physics Neutrino Interactions Neutrino Mixing |
| title | Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability |
| title_full | Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability |
| title_fullStr | Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability |
| title_full_unstemmed | Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability |
| title_short | Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability |
| title_sort | theory of neutrino fast flavor evolution part ii solutions at the edge of instability |
| topic | Neutrino Interactions Neutrino Mixing |
| url | https://doi.org/10.1007/JHEP12(2024)205 |
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