  Unification ideas motivate the formulation of field equations on an extended
spin space. Demanding that the Poincare symmetry be maintained, one derives
scalar symmetries that are associated with flavor and gauge groups. Boson and
fermion solutions are obtained with a fixed representation. A field theory can
be equivalently written and interpreted in terms of elements of such space and
is similarly constrained. At 5+1 dimensions, one obtains isospin and
hypercharge SU(2)_L X U(1) symmetries, their vector carriers, two-flavor
charged and chargeless leptons, and scalar particles. Mass terms produce
breaking of the symmetry to an electromagnetic U(1), a Weinberg's angle with
sin^2(theta_W)=.25, and additional information on the respective coupling
constants. Their underlying spin symmetry gives information on the particles'
masses; one reproduces the standard-model ratio M_Z/M_W, and predicts a Higgs
mass of M_H ~114 GeV, at tree level.
