Neutrino-anti-neutrino instability in dense neutrino systems, with applications to the early universe and to supernovae

TL;DR

This paper identifies a new fast instability in dense neutrino systems caused by standard interactions, which could significantly impact early universe meson production and supernova neutrino dynamics.

Contribution

It introduces a previously overlooked instability mechanism in dense neutrino environments due to standard Z exchange interactions.

Findings

Discovery of a new fast neutrino-antineutrino mixing instability.

Potential to produce keV-mass pseudoscalar mesons in the early universe.

Implications for neutrino behavior in supernovae environments.

Abstract

We exhibit a new instability that leads to "fast" coherent neutrino-antineutrino mixing in a dense neutrino cloud, arising from the standard four-Fermi interaction induced by Z exchange, and overlooked in the big existing literature on fast processes in this venue. It can play an essential role in creation of an abundance of pseudoscalar mesons of mass in the KeV range in the early universe, at temperatures in the range 10-100 MeV. Also it can overpower existing calculations in the "neutrino bulb" regions of the supernova cloud.