Famously, classical general relativity tells us that black holes “have no hair”: the mass, electric charge, and angular momentum of the black hole are the only parameters about the black hole measurable by us “outside the horizon” observors. Silly me it was only today while exercising that I realized that it might be interesting to ask if black holes can carry a charge from a non-abelian gauge theory. While I was pondering this, the other thought I had was that maybe if the theory of nature has multiple gauge fields, not just just the U(1), SU(2), SU(3) we know, but other higher ones, then this the “hair” produced by these theories might help explain the information paradox for black holes. Amazingly, this is deeply related to the content of some ideas about string theory and black holes!
Update 11/14/03: and of course, embarrassingly, there is this famous paper as pointed out by Ben Toner in the comment section.
The Quantum Cardinals