Journal Article

PUBDB-2025-00619

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Theory of neutrino fast flavor evolution. Part II. Solutions at the edge of instability

Fiorillo, D. F. G. (Corresponding author)DESY* ; Raffelt, G. G.

2024
Springer Heidelberg

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Please use a persistent id in citations: doi:10.1007/JHEP12(2024)205  doi:10.3204/PUBDB-2025-00619

Report No.: arXiv:2409.17232

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.

Keyword(s): neutrino, angular distribution ; velocity, phase ; symmetry, axial ; photon, velocity ; dimension, 1 ; stability ; flavor ; collective ; neutron star ; dispersion relation ; hydrodynamics ; supernova ; Neutrino Interactions ; Neutrino Mixing

Note: 24 pages, 3 figures, version published on JHEP

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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. DFG project G:(GEPRIS)283604770 - SFB 1258: Neutrinos und Dunkle Materie in der Astro- und Teilchenphysik (NDM) (283604770) (283604770)
3. 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

Appears in the scientific report 2024

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Database coverage:
; ; ; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; DOAJ Seal ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; National-Konsortium ; SCOAP3 sponsored Journal ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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