4D DOUBLETON CONFORMAL THEORIES, CPT AND IIB STRINGS ON ADS(5)XS(5)

We study the unitary supermultiplets of the N = 8 d = 5 anti-de Sitter (AdS) superalgebra SU(2,2/4) which is the symmetry algebra of the IIB string theory on AdS(5) x S-5. We give a complete classification of t he doubleton supermultiplets of SU(2,2/4) which do not have a Poincare limit and correspond to d = 4 conformal field theories (CFT) living o n the boundary of AdS5. The CPT self-conjugate irreducible doubleton s upermultiplet corresponds to d = 4 N = 4 super Yang-Mills theory. The other irreducible doubleton supermultiplets come in CPT conjugate pair s. The maximum spin range of the general doubleton supermultiplets is 2. In particular, there exists a CPT conjugate pair of doubleton super multiplets corresponding to the fields of N = 4 conformal supergravity in d = 4 which can be coupled to N = 4 super Yang-Mills theory in d = 4. We also study the ''massless'' supermultiplets of SU(2,2/4) which can be obtained by tensoring two doubleton supermultiplets. The CPT se lf-conjugate ''massless'' supermultiplet is the N = 8 graviton supermu ltiplet in AdS5. The other ''massless'' supermultiplets generally come in conjugate pairs and can have maximum spin range of 4. We discuss t he implications of our results for the conjectured CFT/AdS dualities. (C) 1998 Published by Elsevier Science B.V.