Description
In this talk, I will present our recent work on post-Minkowskian EFT for scalar-tensor theories and boson stars. We first derive the analytical expressions of the scattering angle using PM-EFT techniques for both the cases, and in particular provide the first analytical treatment of boson stars as a two-body problem. We then derive the effective-one-body description of these systems. We then compare analytic results to the scattering angle extracted from sequences of numerical-relativity simulations at fixed energy, varying impact parameter, and coupling strength. We find excellent agreement for both the cases. In particular for boson stars, the very good agreement exhibits the attractive (repulsive) effect of in-phase (out-of-phase) binaries. For small impact parameters, where the stars approach more closely before separating to infinity, the scalar-field interaction is found to dominate.