Derivative interactions in de Rham-Gabadadze-Tolley massive gravity

We investigate the possibility of a new massive gravity theory with derivative interactions as an extension of de Rham-Gabadadze-Tolley massive gravity. We find the most general Lagrangian of derivative interactions using a Riemann tensor whose cutoff energy scale is Lambda(3), which is consistent with de Rham-Gabadadze-Tolley massive gravity. Surprisingly, this infinite number of derivative interactions can be resummed with the same method in de Rham-Gabadadze-Tolley massive gravity, and remaining interactions contain only two parameters. We show that the equations of motion for scalar and tensor modes in the decoupling limit contain fourth derivatives with respect to spacetime, which implies the appearance of ghosts at Lambda(3). We claim that consistent derivative interactions in de Rham-Gabadadze-Tolley massive gravity have a mass scale M, which is much smaller than the Planck mass M-Pl.