Free large N supersymmetric Yang-Mills theory as a string theory

The strong version of Maldacena's AdS/CFT conjecture implies that the large Nexpansion of free N=4 super-YM theory describes an interacting string theory inthe extreme limit of high spacetime curvature relative to the string length.String states may then be understood as composed of SYM string bits. Weinvestigate part of the low-lying spectrum of the tensionless (zero-coupling)limit and find a large number of states that are not present in the infinitetension (strong-coupling) limit, notably several massless spin two particles.We observe that all conformal dimensions are N-independent in the free SYMtheory, implying that masses in the corresponding string theory are unchangedby string interactions. Degenerate string states do however mix in theinteracting string theory because of the complicated N-dependence of generalCFT two-point functions. Finally we verify the CFT crossing symmetry, whichcorresponds to the dual properties of string scattering amplitudes. This meansthat the SYM operator correlation functions define AdS dual models analogous tothe Minkowski dual models that gave rise to string theory.Comment: LaTeX2e, 15 pages, 3 figures, uses youngtab.sty; v2: references on tensionless strings adde