Effective average action and nonperturbative renormalization group equation in higher derivative quantum gravity

TL;DR

This paper investigates the nonperturbative renormalization group flow in higher derivative quantum gravity using the effective average action, revealing antiscreening or screening of Newtonian coupling and discussing UV fixed points.

Contribution

It introduces a nonperturbative RG framework for $R^2$-gravity in a de Sitter background, addressing gauge dependence and analyzing the behavior of gravitational couplings.

Findings

Antiscreening or screening behavior of Newtonian coupling depending on higher-derivative couplings

Existence of unstable UV fixed points in the RG flow

Gauge dependence issues are resolved in the Landau-De Witt gauge

Abstract

We study the exact renormalization group (RG) in $R^2$-gravity in the effective average action formalism using the background field method. The truncated evolution equation (where truncation is made to low-derivatives functionals space) for such a theory in a de Sitter background leads to a set of nonperturbative RG equations for cosmological and gravitational coupling constants. The gauge dependence problem is solved by working in the physical Landau-De Witt gauge corresponding to gauge-fixing independent effective action. Approximate solution of nonperturbative RG equations reveals the appearence of antiscreening or screening behaviour of Newtonian coupling, depending on the higher-derivatives coupling constants. The existence of unstable UV fixed points is also mentioned.