# Yang-Mills conformal gravity

Playing this video requires the latest flash player from Adobe.

We reconsider a gauge theory of gravity in which the gauge group is the conformal group SO(4,2), and the action is of the Yang-Mills form, quadratic in the curvature. The vacuum sector of the resulting gravitational theory exhibits local conformal symmetry. We allow for conventional matter coupled to the spacetime metric as well as matter coupled to the field that gauges special conformal transformations. When the theory is linearized about flat space, we find there is a long range gravitational force in addition to Newton’s inverse square law. Furthermore, the cosmological sector of the theory exhibits late time acceleration, an early time bounce, and a post-bounce quasi-de Sitter inflationary'' phase of arbitrary duration (without an inflaton).