Spherically symmetric solutions of Einstein + non-polynomial gravities

Understand

We obtain the static spherically symmetric solutions of a class of gravitational models whose additions to the General Relativity (GR) action forbid Ricci-flat, in particular, Schwarzschild geometries.

• These theories are selected to maintain the (first) derivative order of the Einstein equations in Schwarzschild gauge.
• Generically, the solutions exhibit both horizons and a singularity at the origin, except for one model that forbids spherical symmetry altogether.
• Extensions to arbitrary dimension with a cosmological constant, Maxwell source and Gauss-Bonnet terms are also considered.