  We calculate tree-level scattering amplitudes of massive spin-2 KK particles
in models of stabilized compact extra-dimensional theories. Naively introducing
a mass for the radion in an extra-dimensional model without accounting for the
dynamics responsible for stabilizing the extra dimension upsets the
cancellations relating the masses and couplings of the spin-2 modes, resulting
in KK scattering amplitudes which grow like $E^{4}$ instead of $E^{2}$. We
therefore investigate scattering of the Kaluza-Klein states in theories
incorporating the Goldberger-Wise mechanism to stabilize the size of the extra
dimension. We demonstrate that the cancellations occur only when one includes
not only the massive radion, but also the massive spin-0 modes arising from the
Goldberger-Wise scalar. We compute the revised sum rules which are satisfied in
a stabilized model to ensure a consistent high-energy scattering amplitude. We
introduce a simple model of a stabilized extra dimension which is a small
deformation of a flat (toroidal) five-dimensional model, and demonstrate the
cancellations in computations performed to leading nontrivial order in the
deformation. These results are the first complete KK scattering computation in
an extra-dimensional model with a stabilized extra dimension, with implications
for the theory and phenomenology of these models.
