Cosmological and astrophysical tests of quantum gravity

TL;DR

This paper explores how quantum gravity effects near a fixed point could connect the cosmological constant and galactic rotation phenomena through a renormalization group framework involving a correlation length.

Contribution

It proposes a model where the quantum effective action depends on a correlation length, linking quantum gravity, the cosmological constant, and galactic dynamics.

Findings

The cosmological constant scales as the inverse square of the correlation length.

Quantum gravity effects modify Newtonian dynamics at low acceleration scales.

Renormalization group effects could unify explanations for dark energy and galactic rotation curves.

Abstract

Physics in the vicinity of an ultraviolet stable fixed point of a quantum field theory is parametrized by a renormalization group invariant macroscopic length scale, the correlation length $\xi,$ with the quantum effective action a function of this length scale. Numerical simulations of quantum gravity suggest the existence of just such a fixed point. Since the quantum effective action is a function only of $\xi,$ the cosmological constant must be $k \xi^{-2}$ with $k$ a pure number. Higher derivative terms are also parametrized by this length scale, so in particular the effective Newtonian dynamics of a test particle is modified at acceleration scales of order $1/\xi.$ Thus, renormalization group effects in quantum gravity provide a natural link between the phenomenological acceleration scale associated with galactic rotation curves and the value of the cosmological constant favoured by recent supernovae observations.