Strong Coupling and Bounds on the Graviton Mass in Massive Gravity
  The theory of a single massive graviton has a cutoff much below its Planck
scale, because the extra modes from the graviton multiplet involve higher
derivative self-interactions, controlled by a scale convoluted from the small
graviton mass. Generically, these correct the propagator by environmental
effects. The resulting effective cutoff depends on the environmental parameters
and the graviton mass. Requiring the theory to be perturbative down to ${\cal
O}(1) mm$, we derive bounds on the graviton mass, corresponding to $\gtrsim
{\cal O}(1) meV$ for the generic case, and somewhat weaker bounds in cases of
fine-tuning. In all cases the mass is required to be much too large for the
theory to conform with GR at cosmological distances. Similar results also hold
in quartic and quintic Galileon theory.
