(Springer, 2008) Li, Wei; Song, Wei; Strominger, Andrew
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)).
