  We show that holography poses non-trivial restrictions on various couplings
of an interacting field. For a vector boson in the AdS Reissner-Nordstrom
background, the dual boundary theory is pathological unless its electromagnetic
and gravitational multipole moments are constrained. Among others, a generic
dipole moment afflicts the dual CFT with superluminal modes, whose remedy
bounds the gyromagnetic ratio in a range around the natural value g=2. We
discuss the CFT implications of our results, and argue that similar
considerations can shed light on how massive higher-spin fields couple to
electromagnetism and gravity.

High Energy Physics - Theory