2022/01/17 by Simon Caron-Huot, Yue-Zhou Li, Julio Parra-Martinez +1 · 1 voice · 1 citation
Physics and Astronomy · #hep-th #gr-qc #hep-ph
paper · pdf · doi:10.1007/jhep05(2023)122
We study constraints from causality and unitarity on 2→2 graviton scattering in four-dimensional weakly-coupled effective field theories. Together, causality and unitarity imply dispersion relations that connect low-energy observables to high-energy data. Using such dispersion relations, we derive two-sided bounds on gravitational Wilson coefficients in terms of the mass M of new higher-spin states. Our bounds imply that gravitational interactions must shut off uniformly in the limit G → 0, and prove the scaling with M expected from dimensional analysis (up to an infrared logarithm). We speculate that causality, together with the non-observation of gravitationally-coupled higher spin states at colliders, severely restricts modifications to Einstein gravity that could be probed by experiments in the near future.