We discuss photon Bremsstrahlung induced by virtual graviton exchange in
proton-proton interactions at hadronic colliders, resulting from the exchange
of Kaluza-Klein excitations of the graviton. The relevant subprocesses, gg to G
to e^+e^-gamma and q barq to e^+e^-gamma are discussed in both the ADD and the
RS scenarios. Although two-body final states (or real graviton emission) would
presumably be the main discovery channels, a search for three-body final states
could be worthwhile since such events have characteristic features that could
provide additional confirmation. In particular, the k_perp-distribution of the
photon is in both scenarios harder than that of the Standard-model background.Comment: 24 pages, including figures. v2: Including initial-state
Bremsstrahlung and photon k_perp spectra. Version to appear in PR