  In a preceding report (hep-th/0112261), Pierre Ramond outlined a programme we
have followed recently. An important ingredient in a future unique theory for
basic physics must be a unique mathematical structure. It is then interesting
to investigate the underlying mathematical structure of 11-dimensional
space-time. A search for exceptional group structures specific to eleven
dimensions leads us then to a study of the coset F_4/SO(9),which may provide a
generalization of eleven-dimensional supergravity. This scheme is more general
though and in this report we will show the corresponding structure related to
the coset SU(3)/SU(2) x U(1), where we interpret the U(1) as the helicity group
in four dimensions.
