The Consistency of Scalar Gauss-Bonnet Gravity

The shape of Scalar Gauss-Bonnet Gravity

We study the consistency of scalar gauss-bonnet gravity, a generalization of general relativity where black holes can develop non-trivial hair by the actionof a coupling between a function of a scalar field and the gauss-bonnet invariant of the space-time.These constrain the value of all even derivatives of the function and are highly restrictive.They require some of the scalesof the theory to be of planckian order, and rule out most of the models used in the literature for black hole scalarization.