The scalar field associated with fluctuations in the positions of the two branes, the ``radion'', plays an important role determining the cosmology and collider phenomenology of the Randall-Sundrum solution to the hierarchy problem. It is now well known th

10

100

1000m h = m r [GeV]0.0010.010.11−1−0.5

−0.2

0|a 0|101001000m h = m r [GeV]0.0010.010.11

−1.5

−1−0.50

|a 0|Figure 6:The contribution to the j =0partial wave amplitude a 0from all tree-level diagrams,including the mass effects of Higgs and the radion.The x -axis corresponds to the interaction eigenstate masses of the Higgs and radion (taken to be equal for illustration).The scattering amplitude was evaluated at the maximal energy

√2,

and so there are always significant contributions to the partial wave amplitude from these mass terms.We illustrate this in Fig.6in two cases with √s =Λ=5TeV and various values of ξ.The interaction

eigenstate masses are shown on the axes,although they are nearly the same as the the physical masses throughout the plot.Thus,requiring perturbative unitarity is not violated places upper bounds on the masses of the mixed scalars (radion and Higgs),in regions of (γ,ξ)parameter space allowed by Fig.5.

The contributions to the partial wave amplitude above the Higgs and radion mass poles always constructively interfere,and so the presence of a radion universally increases the size of the partial wave amplitude.Below the mass of the Higgs and the radion √