ILQG: Loop Quantum Gravity as a Topological Field Theory with Defects
I propose a reformulation of covariant loop quantum gravity as a topological field theory with defects. The physical degrees of freedom are carried along a number of intersecting submanifolds, which appear as topological defects in the model. Looking at an equal time-slice these defects organize themselves so as to form a LQG spin network. The underlying classical action is an integral over two- and three-dimensional surfaces plus boundary terms at their mutual intersection. For the equations of motion to be satisfied certain integrability conditions have to be imposed, which require the local gauge group to be SO(2,3).