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 AdS(5) 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 g(2)) and in AdS(5) supergravity. Surprisingly, the one-loop result shows that the two functions determining the amplitude coincide while in the supergravity regime they are distinct v different. We discuss the possible implications of this perturbative degeneracy for the AdS/CFT correspondence. (C) 2003 Elsevier B.V. All rights reserved.