Collider signals of gravitational fixed points

Recent studies have shown that the poor perturbative behavior of General Relativity in the ultraviolet regime may be ameliorated by the existence of a non-Gaussian fixed point which renders the theory asymptotically safe and possibly non-perturbatively renormalizable. This results in a running of the (effective) gravitational coupling such that gravity becomes weaker at high energies. We parameterize this effective coupling with a form factor and study its consequences at the LHC and ILC in models with large extra dimensions or warped extra dimensions. We find significant effects in the processes of Kaluza-Klein (KK) graviton exchange or resonant KK graviton production in both the Drell-Yan reaction as well as in e+e−→f. On the otherhand, processes leading to KK graviton emission show qualitatively less sensitivity to the presence of a form factor. In addition, we examine tree-level perturbative unitarity in 2→2 gravity-mediated scattering and find that this form factor produces a far better behaved amplitude at large center of mass energies.

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