Chiral Gravity in Three Dimensions

TL;DR

This paper investigates a modified three-dimensional gravity theory with a gravitational Chern-Simons term, revealing a special critical point where the theory becomes chiral and potentially dual to a right-moving boundary conformal field theory.

Contribution

It demonstrates that at a critical coupling, the massive gravitons vanish, leading to a chiral gravity theory with specific boundary CFT duality conjecture.

Findings

Massive gravitons become massless at the critical point.

BTZ black holes have equal mass and angular momentum at the critical point.

The theory is conjectured to be dual to a right-moving boundary CFT with specific central charges.

Abstract

Three dimensional Einstein gravity with negative cosmological constant -1/\ell^2 deformed by a gravitational Chern-Simons action with coefficient 1/\mu is studied in an asymptotically AdS_3 spacetime. It is argued to violate unitary or positivity for generic \mu due to negative-energy massive gravitons. However at the critical value \mu\ell=1, the massive gravitons disappear and BTZ black holes all have mass and angular momentum related by \ell M=J. The corresponding chiral quantum theory of gravity is conjectured to exist and be dual to a purely right-moving boundary CFT with central charges (c_L,c_R)=(0,3\ell /G).