  The Euklidean correlation functions and vacuum expectation values of products
of field operators of some Lorentz spin and dimension are expressed through
Mellin amplitudes which depend on complex dimensions subject to linear
constraints. The constraints can be solved in terms of conserved momenta whose
squares are given by the field dimensions, and related Mandelstam variables s.
The Mellin amplitudes furnish a universal representation of conformal field
theories without explicit reference to D. The costumary principles of quantum
field theory plus conformal invariance and operator product expansions (OPE)
say that the Mellin amplitudes are amplitudes of dual resonance models with
exact duality and a form of factorization which follows from OPE. Fields in the
OPE with spin l and dimension d produce simple poles in the scalar 4-point
Mellin amplitude at s=d-l+2n, n=0,1,2,3... with polynomial residues. The
leading pole determines the satellites n=1,2,3...
