Representations of (1,0) and (2,0) superconformal algebras in six dimensions: massless and short superfields

We construct unitary representations of (1,0) and (2,0) superconformal algebras in six dimensions by using superfields defined on harmonic superspaces with coset manifolds USp(2n)/[U(1)] /sup n/, n=1,2. In the spirit of the AdS/sub 7//CFT/sub 6/ correspondence, massless conformal fields correspond to "supersingletons" in AdS/sub 7/. By tensoring them we produce all short representations corresponding to 1/2 and 1/4 BPS anti-de Sitter bulk states of which "massless bulk" representations are particular cases. (33 refs).