  The Blandford-Znajek process, which uses a magnetized plasma to extract
energy from a rotating black hole, is one of the leading candidates for
powering relativistic jets. In this work, we investigate the Blandford-Znajek
process in two well-motivated quadratic gravity theories: scalar Gauss-Bonnet
and dynamical Chern-Simons gravity. We solve analytically for a split-monopole
magnetosphere to first order in the small-coupling approximation and second
relative order in the slow-rotation approximation. The extracted power at fixed
spin and magnetic flux is enhanced in scalar Gauss-Bonnet and reduced in
dynamical Chern-Simons gravity, compared to general relativity. We find that
there is a degeneracy between spin and the coupling constants of the theories
at leading order in the slow rotation approximation that is broken at higher
orders.
