Light deflection in semiclassical higher-derivative gravity

Higher-derivative gravity, i.e. the system defined by General Relativity’s Lagrangian augmented by curvature-squared terms, is a renormalizable gravity model, along with its matter couplings. This model has two free parameters, α and β, which couple the higher-order terms R² and $R_{\mu \nu }^2$, respectively. In this work we study the bending of light in the framework of higher-derivative gravity utilizing both classical and semiclassical approaches. We show that the Ricci-squared sector is associated to a repulsive interaction and, at the tree-level, yields dispersive propagation of photons yet in first order. Also, a comparison between the predicted results and experimental data allows us to set an upper bound on the coupling constant β.