Brane baldness versus superselection sectors - art. no. 105007

The search for intersecting brane solutions in supergravity is a large and profitable industry. Recently, attention has focused on finding localized f orms of known "delocalized" solutions. However, in some cases, a localized version of the delocalized solution simply does not exist. Instead, localiz ed separated branes necessarily delocalize as the separation is removed. Th is phenomenon is related to black hole no-hair theorems, i.e., "baldness." We continue the discussion of this effect and describe how it can be unders tood, in the case of Dirichlet branes, in terms of the corresponding inters ection field theory. When it occurs, it is associated with the quantum mixi ng of phases and lack of superselection sectors in low dimensional field th eories. We find surprisingly wide agreement between the field theory and su pergravity both with respect to which examples delocalize and with respect to the rate at which this occurs. [S0556-2821(99)07418-4].