Towards singularity and ghost free theories of gravity
arXiv:1110.5249 · doi:10.1103/PhysRevLett.108.031101
Abstract
We present the most general covariant ghost-free gravitational action in a Minkowski vacuum. Apart from the much studied f(R) models, this includes a large class of non-local actions with improved UV behavior, which nevertheless recover Einstein's general relativity in the IR.
4 pages; redundancies in action eliminated; references added and a few minor typos corrected