Self-induced spectral splits in supernova neutrino fluxes

TL;DR

This paper investigates the phenomenon of spectral splits in supernova neutrino fluxes caused by collective flavor transformations due to neutrino-neutrino interactions, providing explicit solutions and analytic expressions.

Contribution

It offers an explicit solution and analytic expressions for spectral splits in supernova neutrino fluxes in the adiabatic limit, advancing understanding of flavor transformations.

Findings

Spectral splits are caused by adiabatic transitions in neutrino density.

E_split is determined by flavor-lepton number conservation.

Analytic expressions for spectral splits are derived.

Abstract

In the dense-neutrino region above the neutrino sphere of a supernova (r > 400 km), neutrino-neutrino refraction causes collective flavor transformations. They can lead to "spectral splits" where an energy E_split splits the transformed spectrum sharply into parts of almost pure but different flavors. Unless there is an ordinary MSW resonance in the dense-neutrino region, E_split is determined by flavor-lepton number conservation alone. Spectral splits are created by an adiabatic transition between regions of large and small neutrino density. We solve the equations of motion in the adiabatic limit explicitly and provide analytic expressions for a generic example.