Gravitational photon-photon scattering in a recent unified gravity model

We compute the cross section for photon–photon scattering mediated by single-graviton exchange within the Unified Gravity in Minkowski metric (UGM) recently proposed by Partanen and Tulkki. A central result of this work is that, for small scattering angles, the derived differential cross section reproduces the classical description of the gravitational field produced by light as obtained by Tolman, Ehrenfest, and Podolsky. This agreement provides a nontrivial consistency check between the UGM framework, perturbative quantum gravity, and classical general relativity. We also comment on earlier calculations of gravitational light-by-light scattering by Boccaletti et al. and Barker et al. within the quantum linearized theory of gravitation.