Strong coupling versus 4D locality in induced gravity

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Abstract
We reexamine the problem of strong coupling in a regularized version of Dvali-Gabadadze-Porrati (DGP) (or “brane-induced”) gravity. We find that the regularization of Kolanovic, Porrati, and Rombouts [Phys. Rev. D 68, 064018 (2003)] differs from DGP in that it does not exhibit strong coupling or ghosts up to cubic order in the interactions. We suggest that the nonlocal nature of the theory, when written in terms of the 4D metric, is a plausible reason for this phenomenon. Finally, we briefly discuss the possible behavior of the model at higher order in perturbation theory.