  In AdS, scalar fields with masses slightly above the Breitenlohner-Freedman
bound admit a variety of possible boundary conditions which are reflected in
the Lagrangian of the dual field theory. Generic small changes in the AdS
boundary conditions correspond to deformations of the dual field theory by
multi-trace operators. Here we extend this discussion to the case of vector
gauge fields in the bulk spacetime using the results of Ishibashi and Wald
[hep-th/0402184]. As in the context of scalar fields, general boundary
conditions for vector fields involve multi-trace deformations which lead to
renormalization-group flows. Such flows originate in ultra-violet CFTs which
give new gauge/gravity dualities. At least for AdS4/CFT3, the dual of the bulk
photon appears to be a propagating gauge field instead of the usual R-charge
current. Applying similar reasoning to tensor fields suggests the existence of
a duality between string theory on AdS4 and a quantum gravity theory in three
dimensions.
