ASYMPTOTIC SAFETY IN HIGHER-DERIVATIVE GRAVITY

We study the nonperturbative renormalization group flow of higher-derivative gravity employing functional renormalization group techniques. The nonperturbative contributions to the beta-functions shift the known perturbative ultraviolet fixed point into a nontrivial fixed point with three UV-attractive and one UV-repulsive eigendirections, consistent with the asymptotic safety conjecture of gravity. The implication of this transition on the unitarily problem, typically haunting higher-derivative gravity theories, is discussed.