Minimal Log Gravity

TL;DR

This paper explores exact non-Einstein solutions in Minimal Massive Gravity at the chiral point, revealing diverse asymptotic behaviors, finite conserved charges, and implications for the theory's boundary conditions and Birkhoff theorem.

Contribution

It provides a detailed analysis of non-linear solutions in MMG at the chiral point, including deformations of BTZ black holes and time-dependent geometries, expanding understanding of the theory's solution space.

Findings

Found analytic solutions as deformations of extremal BTZ black holes.

Discovered time-dependent solutions obeying Brown-Henneaux boundary conditions.

Showed solutions have finite mass and angular momentum despite altered asymptotics.

Abstract

Minimal Massive Gravity (MMG) is an extension of three-dimensional Topologically Massive Gravity that, when formulated about Anti-de Sitter space, accomplishes to solve the tension between bulk and boundary unitarity that other models in three dimensions suffer from. We study this theory at the chiral point, i.e. at the point of the parameter space where one of the central charges of the dual conformal field theory vanishes. We investigate the non-linear regime of the theory, meaning that we study exact solutions to the MMG field equations that are not Einstein manifolds. We exhibit a large class of solutions of this type, which behave asymptotically in different manners. In particular, we find analytic solutions that represent two-parameter deformations of extremal Banados-Teitelboim-Zanelli (BTZ) black holes. These geometries behave asymptotically as solutions of the so-called Log Gravity, and, despite the weakened falling-off close to the boundary, they have finite mass and finite angular momentum, which we compute. We also find time-dependent deformations of BTZ that obey Brown-Henneaux asymptotic boundary conditions. The existence of such solutions show that Birkhoff theorem does not hold in MMG at the chiral point. Other peculiar features of the theory at the chiral point, such as the degeneracy it exhibits in the decoupling limit of the Cotton tensor, are discussed.