Graviton Production By Two Photon and Electron-Photon Processes In Kaluza-Klein Theories With Large Extra Dimensions

We consider the production of gravitons via two photon and electron-photon fusion in Kaluza-Klein theories which allow TeV scale gravitational interactions. We show that at electron-positron colliders, the processes ll → ll + graviton, with l = e, μ, can lead to a new signal of low energy gravity of the form ll → ll+missing energy which is well above the Standard Model background. For example, with two extra dimensions at the Next Linear Collider with a center of mass energy of 500 or 1000 GeV, hundreds to thousands such ll + graviton events may be produced if the scale of the gravitational interactions, MD, is around a few TeV. At a gamma-electron collider, more stringent bounds may be placed on MD via the related reaction e−γ → e−G. For instance, if a 1 TeV ee collider is converted to an electron-photon collider, a bound of ∼ 10 TeV may be placed on the scale MD if the number of extra dimensions δ = 2 while a bound of ∼ 4 TeV may be placed if δ = 4. email: [email protected] email: [email protected] email: [email protected]