During my Master's degree, we studied Black Holes as solutions of Einstein-Maxwell equations, and I was wondering if it would be possible to also add strong or electroweak forces in the classic non-quantum version of General Relativity, i.e. to extend the U(1) electromagnetic symmetry to a non-abelian group SU(N).
I mean, we saw that in a certain way it could be done with the Kaluza-Klein mechanism, but this method has some problems so I don't know if it would be possible in general to find a solution of this kind just by solving the field equations.
What about the same problem in Supergravity?