High Energy Theory Seminar

While the canonical formulation of graviton perturbation theory is calculationally complex, the freedoms of nonlinear field redefinition and gauge fixing allow for immense simplification and the uncovering of new structures in perturbative gravity. In particular, we recast the Einstein-Hilbert action into a form that is invariant to all orders under a twofold Lorentz symmetry suggestive of the double copy between gauge theory and gravity. Furthermore, we derive field bases in which graviton perturbation theory is drastically simplified. We find a purely cubic formulation of perturbative gravity via the introduction of a single auxiliary field. With a different judicious choice of field redefinition and gauge fixing, we construct an especially compact form for the Einstein-Hilbert action in which all graviton interactions are simply proportional to the graviton kinetic term. All of our results can be extended to perturbation about curved background spacetimes.