Background fields in 2+1 topological gravity

Abstract

The partition function of 2+1 Chern-Simons Witten topological gravity has an attractive physical interpretation in terms of the unbroken and broken phases of gravity. We make this physical interpretation manifest by using the background field method.

Quantum Einstein gravity as a topological field theory

“…Something along these lines is witnessed in 2+1 dimensions where 2+1 dimensional quantum gravity can be given a gauge theoretic interpretation in terms of a Chern-Simons theory with gauge group ISO(2, 1), SO (3,1) or SO(2, 2), depending on whether the cosmological constant λ is zero, positive or negative [3,4]. This theory has two natural phases depending on wheather a certain operator has zero modes or not and it is argued that each of these phases corresponds to the unbroken and broken phases of gravity [4,5].…”