On a large N degeneracy in N=4 SYM and the AdS/CFT correspondence

We study the four-point correlator of 1/2-BPS operators of weight 4 in N=4 SYM, which are dual to massive KK modes in AdS5 supergravity. General field-theoretic arguments lead to a partially non-renormalized form of the amplitude that depends on two a priori independent functions of the conformal cross-ratios. We explicitly compute the amplitude in the large N limit at one-loop (order g2) and in AdS5 supergravity. Surprisingly, the one-loop result shows that the two functions determining the amplitude coincide while in the supergravity regime they are distinctly different. We discuss the possible implications of this perturbative degeneracy for the AdS/CFT correspondence