  We consider the novel Kaluza-Klein (KK) scenario where gravity propagates in
the $4+n$ dimensional bulk of spacetime, while gauge and matter fields are
confined to the 3+1 dimensional world-volume of a brane configuration. For
simplicity we assume compactification of the extra $n$ dimensions on a torus
with a common scale $R$, and identify the massive KK states in the
four-dimensional spacetime. For a given KK level $\vec{n}$ there are one spin-2
state, $(n-1)$ spin-1 states and $n(n-1)/2$ spin-0 states, all mass-degenerate.
We construct the effective interactions between these KK states and ordinary
matter fields (fermions, gauge bosons and scalars). We find that the spin-1
states decouple and that the spin-0 states only couple through the dilaton
mode. We then derive the interacting Lagrangian for the KK states and Standard
Model fields, and present the complete Feynman rules. We discuss some low
energy phenomenology for these new interactions for the case when 1/R is small
compared to the electroweak scale, and the ultraviolet cutoff of the effective
KK theory is on the order of 1 TeV.

High Energy Physics - Phenomenology;High Energy Physics - Theory