Collective flavor conversion in dense neutrino plasmas
Abstract
Compact transient sources, such as supernovae (SNe) and neutron star mergers (NSMs), host a population of thermal neutrinos in their inner cores, which decouple from the dense matter as they stream out. Yet, collisionless does not mean free; their density is large enough to mediate collective waves driven by the coherent weak neutrino--neutrino interaction. These collective waves carry little energy, but crucially they transport flavor. Neutrinos thus form a collisionless plasma with flavor transport driven by flavor waves, whose quanta are called flavomons ψ. The wavelength of these flavomons is much shorter than the characteristic scales of SNe and NSMs, so that a brute-force numerical treatment of the neutrino plasma is beyond our capabilities. Yet flavomons cannot be neglected, as the stimulated neutrino decays, schematically ν̅e→ ν̅μψ, cause a rapid buildup in their population, more conventionally called a flavor instability. We review the theory of the neutrino plasma, and systematically discuss the instabilities leading to flavomon growth, and connect this emerging quasiparticle description with recent advances in numerical neutrino flavor kinetics.
Related
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BibTeX
@misc{fiorillo2026collective,
title = {{Collective flavor conversion in dense neutrino plasmas}},
author = {Damiano F. G. Fiorillo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.19256},
eprint = {2609.19256},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.19256},
}
RIS
TY - UNPB
TI - Collective flavor conversion in dense neutrino plasmas
AU - Damiano F. G. Fiorillo
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2609.19256
UR - https://arxiv.org/abs/2609.19256
AB - Compact transient sources, such as supernovae (SNe) and neutron star mergers (NSMs), host a population of thermal neutrinos in their inner cores, which decouple from the dense matter as they stream out. Yet, collisionless does not mean free; their density is large enough to mediate collective waves driven by the coherent weak neutrino--neutrino interaction. These collective waves carry little energy, but crucially they transport flavor. Neutrinos thus form a collisionless plasma with flavor transport driven by flavor waves, whose quanta are called flavomons ψ. The wavelength of these flavomons is much shorter than the characteristic scales of SNe and NSMs, so that a brute-force numerical treatment of the neutrino plasma is beyond our capabilities. Yet flavomons cannot be neglected, as the stimulated neutrino decays, schematically ν̅_e→ ν̅_μψ, cause a rapid buildup in their population, more conventionally called a flavor instability. We review the theory of the neutrino plasma, and systematically discuss the instabilities leading to flavomon growth, and connect this emerging quasiparticle description with recent advances in numerical neutrino flavor kinetics.
ER -