Lepton number crossings are insufficient for flavor instabilities

Fuente: arXiv
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Hauptverfasser: Fiorillo, Damiano F. G., Raffelt, Georg G.
Format: Preprint
Veröffentlicht: 2025
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author Fiorillo, Damiano F. G.
Raffelt, Georg G.
author_facet Fiorillo, Damiano F. G.
Raffelt, Georg G.
contents In dense neutrino environments, the mean field of flavor coherence can develop instabilities. A necessary condition is that the flavor lepton number changes sign as a function of energy and/or angle. Whether such a crossing is also sufficient has been a longstanding question. We construct an explicit counterexample: a spectral crossing without accompanying flavor instability, with an even number of crossings being key. This failure is physically understood as Cherenkov-like emission of flavor waves. If flipped-lepton-number neutrinos never dominate among those kinematically allowed to decay, the waves cannot grow.
format Preprint
id arxiv_https___arxiv_org_abs_2507_22987
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lepton number crossings are insufficient for flavor instabilities
Fiorillo, Damiano F. G.
Raffelt, Georg G.
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
In dense neutrino environments, the mean field of flavor coherence can develop instabilities. A necessary condition is that the flavor lepton number changes sign as a function of energy and/or angle. Whether such a crossing is also sufficient has been a longstanding question. We construct an explicit counterexample: a spectral crossing without accompanying flavor instability, with an even number of crossings being key. This failure is physically understood as Cherenkov-like emission of flavor waves. If flipped-lepton-number neutrinos never dominate among those kinematically allowed to decay, the waves cannot grow.
title Lepton number crossings are insufficient for flavor instabilities
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2507.22987