Scattering amplitudes of massive spin-2 Kaluza-Klein states grow only as O (s)

Abstract

We present the results of the first complete calculation of the tree-level 2→2 high-energy scattering amplitudes of the longitudinal modes of massive spin-2 Kaluza-Klein (KK) states, both in the case where the internal space is a torus and in the Randall-Sundrum model where the internal space has constant negative curvature. While individual contributions to this amplitude grow as O(s5), we demonstrate explicitly that intricate cancellations occur between different contributions, reducing the growth to O(s), a slower rate of growth than previously argued in the literature. These cancellations require subtle relationships between the masses of the Kaluza-Klein states and their interactions, and reflect the underlying higher-dimensional diffeomorphism invariance. Our results provide fresh perspective on the range of validity of (effective) field theories involving massive spin-2 KK particles, with significant implications for the theory and phenomenology of these states.