Neutrino Dark Energy With More Than One Neutrino Species

TL;DR

This paper examines the mass varying neutrino model for dark energy, highlighting its stability issues and the challenges in using multiple neutrino species, ultimately questioning its viability as an explanation for dark energy.

Contribution

The paper analyzes stability constraints in multi-neutrino mass varying models and explains why certain approaches to neutrino dark energy are not feasible.

Findings

Stable, natural models with correct dark energy density do not exist.

Using the lightest relativistic neutrino as dark energy is ineffective due to feedback from heavier neutrinos.

The model faces significant stability constraints that limit its applicability.

Abstract

The mass varying neutrino scenario is a model that successfully explains the origin of dark energy while at the same time solves the coincidence problem. The model is, however, heavily constrained by its stability towards the formation of neutrino bound states when the neutrinos become nonrelativistic. We discuss these constraints and find that natural, adiabatic, stable models with the right amount of dark energy today do not exist. Secondly, we explain why using the lightest neutrino, which is still relativistic, as an explanation for dark energy does not work because of a feedback mechanism from the heavier neutrinos.