Conformal Maxwell theory as a singleton field theory on AdS5, IIB 3-branes and duality

We examine the boundary conditions associated with extended supersymmetric Maxwell theory in five-dimensional anti-de Sitter space. Excitations on the boundary are identical to those of ordinary four-dimensional conformal invariant superelectrodynamics. Extrapolations of these excitations give rise to a five-dimensional topological gauge theory of the singleton type. The possibility of a connection between this phenomenon and the world-volume theory of 3-branes in IIB string theory is discussed.