/ 99 04 42 5 v 1 2 2 A pr 1 99 9 SLAC – PUB – 8121 April 1999 γγ → γγ as a Test of Weak Scale Quantum Gravity at the NLC ∗

Recently, it has been proposed that the fundamental scale of quantum gravity can be close to the weak scale if there are large extra dimensions. This proposal has important phenomenological implications for processes at the TeV scale. We study the process γγ → γγ, assuming an ultraviolet cutoff M S ∼ 1 TeV for the effective gravity theory. We find that, at center of mass energies √ s ∼ 1 TeV, the contribution of gravitationally mediated scattering to the cross section is comparable to that coming from the one-loop Feynman diagrams of the Standard Model. We thus conclude that the effects of weak scale quantum gravity can be studied at the Next Linear Collider (NLC), in the photon col-lider mode. Our results suggest that, for typical proposed NLC energies and luminosities, the range 1 TeV < ∼ M S < ∼ 10 TeV can be probed.