title: Strong coupling and bounds on the spin-2 mass in massive gravity.
abstract: The de Rham-Gabadadze-Tolley theory of a single massive spin-2 field has a cutoff much below its Planck scale because the extra modes from the massive spin-2 multiplet involve higher derivative self-interactions, controlled by a scale convoluted from its mass. Generically, these correct the propagator by environmental effects. The resulting effective cutoff depends on the environmental parameters and the spin-2 "graviton" mass. Requiring the theory to be perturbative down to O(1) mm, we derive bounds on the mass, corresponding to ≳O(1) meV for the generic case, assuming the coupling to be given by the standard Newton's constant, and somewhat weaker bounds in cases with fine-tuning. Thus, the theory of a single massive spin-2 can really only be viewed as a theory describing the full nonlinear propagation of a massive spin-2 field on a fixed background and not as an approximation to general relativity.
authors.affiliation: School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: Clare
authors.initials: C
authors.lastname: Burrage
authors.forename: Nemanja
authors.initials: N
authors.lastname: Kaloper
authors.forename: Antonio
authors.initials: A
authors.lastname: Padilla