Surface term, corner term, and action growth in F(Riemann) gravity theory

TL;DR

This paper reformulates F(Riemann) gravity as a second derivative theory, derives boundary and corner terms for non-smooth boundaries, and applies this to evaluate action growth rates in various AdS black hole spacetimes.

Contribution

It introduces a systematic way to derive boundary and corner terms in F(Riemann) gravity and demonstrates its application to compute action growth rates in complex black hole backgrounds.

Findings

Action growth rate matches previous results for Schwarzschild-AdS black holes.

Late time growth rate vanishes in critical Einsteinian cubic gravity.

Boundary terms ensure a well-posed variational principle in F(Riemann) gravity.

Abstract

After reformulating $F($Riemann$)$ gravity theory as a second derivative theory by introducing two auxiliary fields to the bulk action, we derive the surface term as well as the corner term supplemented to the bulk action for a generic non-smooth boundary such that the variational principle is well posed. We also introduce the counter term to make the boundary term invariant under the reparametrization for the null segment. Then as a demonstration of the power of our formalism, not only do we apply our expression for the full action to evaluate the corresponding action growth rate of the Wheeler-DeWitt patch in the Schwarzchild anti-de Sitter black hole for the $F(R)$ gravity and critical gravity, where the corresponding late time behavior recovers the previous one derived by other approaches, but also in the asymptotically Anti-de Sitter black hole for the critical Einsteinian cubic gravity, where the late time growth rate vanishes but still saturates the Lloyd bound.