Graviton-induced bremsstrahlung

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 $g\overrightarrow{g}\overrightarrow{G}{e}^{+}{e}^{-}\gamma$ and $q\overline{q}\to e^{+}{e}^{-}\gamma$ are discussed in both the Arkani-Hamed–Dimopoulos–Dvali and the Randall-Sundrum 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.