Preprint

PUBDB-2025-01244

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Fast flavor pendulum: Instability condition

Fiorillo, D. F. G. (Corresponding author)Extern*DESY* ; Goimil-García, M. ; Raffelt, G. G.

2024

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Report No.: arXiv:2412.09027

Abstract: Even in the absence of neutrino masses, a neutrino gas can exhibit a homogeneous flavor instability that leads to a periodic motion known as the fast flavor pendulum. A well-known necessary condition is a crossing of the angular flavor lepton distribution. In an earlier work, some of us showed that homogeneous flavor instabilities also obey a Nyquist criterion, inspired by plasma physics. This condition, while more restrictive than the angular crossing, is only sufficient if the unstable branch of the dispersion relation is bounded by critical points that both lie under the light cone (points with subluminal phase velocity). While the lepton-number angle distribution, assumed to be axially symmetric, easily allows one to determine the real-valued branch of the dispersion relation and to recognize if instead superluminal critical points exist, this graphical method does not translate into a simple instability condition. We discuss the homogeneous mode in the more general context of the dispersion relation for modes with arbitrary wave number and stress that it plays no special role on this continuum, except for its regular but fragile long-term behavior, owed to its many symmetries.

Note: 15 pages, 6 figures

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Contributing Institute(s):

1. Theoretische Astroteilchenphysik (Z_THAT)

Research Program(s):

1. 613 - Matter and Radiation from the Universe (POF4-613) (POF4-613)
2. ANET - NEUTRINO QUANTUM KINETICS (101087058) (101087058)
3. DFG project G:(GEPRIS)283604770 - SFB 1258: Neutrinos und Dunkle Materie in der Astro- und Teilchenphysik (NDM) (283604770) (283604770)
4. DFG project G:(GEPRIS)390783311 - EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens (390783311) (390783311)

Experiment(s):

1. No specific instrument

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Database coverage:
Published

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Linked articles:

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Journal Article Fiorillo, D. F. G. (Collaboration author)Extern*DESY* ; Goimil-García, M. ; Raffelt, G. G.
Fast flavor pendulum: Instability condition
Physical review / D 111(8), 083028 (2025) [10.1103/PhysRevD.111.083028]2025     Files  Fulltext by arXiv.org BibTeX | EndNote: XML, Text | RIS

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