Self-induced suppression of collective neutrino oscillations in a supernova

TL;DR

This paper studies how collective neutrino oscillations are suppressed in supernovae due to multiangle effects, challenging previous single-angle approximation assumptions and revealing a new suppression mechanism.

Contribution

It demonstrates that the single-angle approximation fails near the neutrinosphere and introduces a new suppression effect arising from multiangle interactions.

Findings

Single-angle approximation predicts oscillations inside the neutrinosphere.

Multiangle calculations show oscillations are suppressed outside the transport region.

A new suppression mechanism is identified due to interplay between dispersion and vacuum oscillations.

Abstract

We investigate collective flavor oscillations of supernova neutrinos at late stages of the explosion. We first show that the frequently used single-angle (averaged coupling) approximation predicts oscillations close to, or perhaps even inside, the neutrinosphere, potentially invalidating the basic neutrino transport paradigm. Fortunately, we also find that the single-angle approximation breaks down in this regime; in the full multiangle calculation, the oscillations start safely outside the transport region. The new suppression effect is traced to the interplay between the dispersion in the neutrino-neutrino interactions and the vacuum oscillation term.