New perturbative solutions of the Kerr-Newman dilatonic black hole field   equations
  This work describes new perturbative solutions to the classical, four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions do not require the black hole to be slowly rotating. The unperturbed solution is taken to be the ordinary Kerr solution, and the perturbation parameter is effectively the square of the charge-to-mass ratio $(Q/M)^2$ of the Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror) symmetry for the theory, which maps the small coupling sector to the strong coupling sector ($\phi \to -\phi$). We also calculate the gyromagnetic ratio of the black hole. 
R. Casadio (INFN, Sezione di Bologna, Italy) B. Harms, Y. Leblanc   (University of Alabama) and P.H. Cox (Texas A&M Universi...