Diphoton signals for Low Scale Gravity in Extra Dimensions

Gravity can become strong at the TeV scale in the theory of extra dimensions. An effective Lagrangian can be used to describe the gravitational interactions below a cut-off scale. In this work, we study the diphoton production in $\gamma\gamma$, $p\bar p$, and $e^+ e^-$ collisions in the model of low scale gravity. Since in the standard model photon-photon scattering only occurs via box diagrams, the cross section is highly suppressed. Thus, photon-photon scattering opens an interesting opportunity for studying the new gravity interaction, which allows tree-level photon couplings. In addition, we also examine the diphoton production at hadronic and $e^+ e^-$ colliders. We derive the limits on the cut-off scale from the available diphoton data and also estimate the sensitivity reach in Run II at the Tevaton and at the future linear $e^+ e^-$ colliders.