General relativity from a gauged Wess-Zumino-Witten term

In this paper two things are done. First it is shown how a four-dimensional gauged Wess-Zumino-Witten term arises from the five-dimensional Einstein-Hilbert plus Gauss-Bonnet Lagrangian with a special choice of the coefficients. Second, the way in which the equations of motion of four-dimensional General Relativity arise is exhibited.

Figure 1

A four-dimensional defect in a six-dimensional manifold. The submanifold $M^4$ has been deleted, as indicated by the infinitesimal loop in the center of the diagram.