Flavomons in Matter Gradients: Ray Tracing and Amplitude Evolution

Abstract

Flavor instabilities develop in neutrino plasmas through the emission of flavomons, the quanta of flavor waves. Matter gradients can sweep flavomons across the unstable wave-number range, halting their amplification. This effect is parametrically small for fast modes, where it was first identified, but we show that it strongly alters neutrino-mass-induced instabilities below the supernova shock, while leaving those outside largely unaffected. The role of these instabilities can therefore be established only through a global treatment beyond local dispersion relations. Using the WKB approximation, we derive the covariant evolution equation for the flavomon amplitude along geometrical-optics rays, enabling a global treatment of instability growth and seeding.

Comments: Substantial textual revisions, corrected amplitude evolution equation, added appendices on formal derivation of the results and on gravitational drifts; 5 pages, 1 figure, plus End Matter and Supplemental Material