A proper fixed functional for four-dimensional Quantum Einstein Gravity

Understand

Realizing a quantum theory for gravity based on Asymptotic Safety hinges on the existence of a non-Gaussian fixed point of the theory's renormalization group flow.

• In this work, we use the functional renormalization group equation for the effective average action to study the fixed point underlying Quantum Einstein Gravity at the functional level including an infinite number of scale-dependent coupling constants.
• We formulate a list of guiding principles underlying the construction of a partial differential equation encoding the scale-dependence of $f(R)$-gravity.
• We show that this equation admits a unique, globally well-defined fixed functional describing the non-Gaussian fixed point at the level of functions of the scalar curvature.