Scales and Hierachies in Asymptotically Safe Quantum Gravity: A Review

Abstract

The asymptotic safety program strives for a consistent description of gravity as a non-perturbatively renormalizable quantum field theory. In this framework the gravitational interactions are encoded in a renormalization group flow connecting the quantum gravity regime at trans-Planckian scales to observable low-energy physics. Our proceedings reviews the key elements underlying the predictive power of the construction and summarizes the state-of-the-art in determining its free parameters. The explicit construction of a realistic renormalization group trajectory describing our world shows that the flow possesses two characteristic scales. The Planck scale where Newton’s coupling G becomes constant is generated dynamically. The freeze-out of the cosmological constant Λ occurs at a terrestrial scale fixed by the observed value of the dimensionless product GΛ. We also review the perspectives of determining the free parameters of the theory through cosmologicalobservations.