Dark energy evolution from quantum gravity

TL;DR

This paper proposes a quantum gravity-based model for dynamical dark energy, linking the evolution of the cosmon field to the renormalization group flow near a fixed point, offering a potential solution to the cosmological constant problem.

Contribution

It introduces a highly predictive quantum gravity framework for dark energy evolution, incorporating scale symmetry violation and neutrino sector effects, which can be tested observationally.

Findings

The model can explain the current dark energy density.

It remains consistent with observational constraints on dark energy evolution.

The approach provides a fundamental explanation for dynamical dark energy.

Abstract

If an ultraviolet fixed point renders quantum gravity renormalizable, the effective potential for a singlet scalar field -- the cosmon -- can be computed according to the corresponding scaling solution of the renormalization group equations. We associate the largest intrinsic mass scale generated by the flow away from the fixed point with the scale of present dark energy density or even smaller. This results in a highly predictive scenario for the evolution of dynamical dark energy. It solves the cosmological constant problem dynamically, and may be called "quantum gravity quintessence". A first setting without quantum scale symmetry violation in the neutrino sector could explain the present amount of dark energy, but fails for the constraints on its time evolution. In contrast, a logarithmic scale symmetry violation in the beyond standard model sector responsible for the neutrino masses induces a non-vanishing cosmon-neutrino coupling in the Einstein frame. This yields a cosmology similar to growing neutrino quintessence, which could be compatible with present observations. The small number of unknown parameters turns the scaling solution for quantum gravity into a fundamental explanation of dynamical dark energy which can be falsified.