Neutrino Dark Energy

TL;DR

This paper explores a novel cosmological model where nonrelativistic neutrinos dynamically increase in mass and behave like dark energy, potentially explaining the dark matter to dark energy transition with a universe less dense than standard models.

Contribution

It introduces a new field theory effect where neutrinos evolve into a state resembling dark energy, linking neutrino properties with cosmic acceleration in an alternative gravity framework.

Findings

Neutrino mass increases as a^{3/2} over time.

Neutrino energy density mimics dark energy behavior.

Total energy density is lower than in fermion-free universe.

Abstract

There exist field theory models where the fermionic energy-momentum tensor contains a term proportional to g_{\mu\nu}\bar{\Psi}\Psi which can be responsible for a dark matter to dark energy transmutation. We study some cosmological aspects of the new field theory effect where nonrelativistic neutrinos are obliged to be drawn into cosmological expansion (by means of dynamically changing their own parameters). This becomes possible as the magnitudes of the cold neutrino and vacuum energy densities are comparable. Some of the features of such Cosmo-Low Energy Physics (CLEP) state in the toy model of the late time universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos: neutrino mass increases as a^{3/2} ($a=a(t)$ is the scale factor); its energy density scales as a sort of dark energy and its equation-of-state approaches w=-1 as a\to\infty; the total energy density of such universe is less than it would be in the universe free of fermionic matter at all. CLEP state can be realized in the framework of an alternative gravity and matter fields theory. The latter is reduced to canonical General Relativity when the fermionic matter built of the first two fermion families is only taken into account. In this case also the 5-th force problem is resolved automatically.