Is the Standard Model in the Swampland? Consistency Requirements from Gravitational Scattering.

We study compatibility of the standard model of particle physics and general relativity by means of gravitational positivity bounds, which provide a necessary condition for a low-energy gravitational theory to be UV completable within the weakly coupled regime of gravity. In particular, we identify the cutoff scale of the standard model coupled to gravity by studying consistency of light-by-light scattering. While the precise value depends on details of the Pomeron effects in QCD, the cutoff scale reads ${10}^{16}\text{ }\text{ }\mathrm{GeV}$ if the single-Pomeron exchange picture works well up to this scale. We also demonstrate that the cutoff scale is lowered to ${10}^{13}\text{ }\text{ }\mathrm{GeV}$ if we consider the electroweak theory without the QCD sector.