Intermediate coupling regime in the AdS/CFT correspondence

The correspondence between the 't Hooft limit of N=4 super Yang-Mills theory and tree-level type-IIB superstring theory on AdS5xS5 in a Ramond-Ramond background at values of λ=g2N ranging from infinity to zero is examined in the context of unitarity. A squaring relation for the imaginary part of the holographic scattering of identical string fields in the two-particle channels is found, and a mismatch between weak and strong 't Hooft coupling is pointed out within the correspondence. Several interpretations and implications are proposed.