Nonlinear/non-iterative treatment of EFT-motivated gravity.

We study a higher derivative extension to General Relativity and present a fully nonlinear/non-perturbative treatment to construct initial data and study its dynamical behavior in spherical symmetry when coupled to a massless scalar field. For initial data, we compare the obtained solutions with those from alternative treatments that rely on a perturbative (or iterative) approach. For the future evolution of such data, we implement a recently introduced approach which addresses mathematical pathologies brought in by the higher derivatives. Our solutions demonstrate the presence of unexpected phenomena -when seen from the lense of General Relativity, as well as departures from General Relativity in the quasi-normal mode behavior of the scalar field scattering off the black hole.