Can we see quantum gravity? Photons in the asymptotic-safety scenario

In the search for a quantum theory of gravity it is crucial to nd experimentalaccess to quantum gravitational e ects. Since these are expected to be very small atobservationally accessible scales it is advantageous to consider processes with no tree-levelcontribution in the standard model, such as photon-photon scattering. We examine theimplications of asymptotically safe quantum gravity in a setting with extra dimensionsfor this case, and point out that various near-future photon-collider setups, employingeither electron or muon colliders, or even a purely laser-based setup, could provide a rstobservational window into the quantum gravity regime