Einstein-Proca Model, Micro Black Holes, and Naked Singularities
  The Einstein-Proca equations, describing a spin-1 massive vector field in general relativity, are studied in the static, spherically-symmetric case. The Proca field equation is a highly nonlinear wave equation, but can be solved to good accuracy in perturbation theory, which should be very accurate for a wide range of mass scales. The resulting first order metric reduces to the Reissner-Nordstrom solution in the limit as the range parameter $\mu$ goes to zero. The additional terms in the $g_{00}$ metric are positive, as in Reissner-Nordstrom, in agreement with previous numerical solutions, and hence involve naked singularities. 
Chris Vuille, James Ipser, and Jeff Gallagher
gr-qc