The Symmetry Reduction from Interactions to Particles
  The hypercharge-isospin-color symmetry of the standard model interaction is drastically reduced to a remaining Abelian electromagnetic $\U(1)$-symmetry for the particles. It is shown that such a symmetry reduction comes as a consequence of the central correlation in the internal group as represented by the standard fields where the hypercharge properties are given by the central isospin-color properties. A maximal diagonalizable symmetry subgroup (Cartan torus) of the interaction group for the particles as eigenvectors has to discard either color (confinement) or isospin. An additional diagonalization for the external spin properties which come centrally correlated with the isospin properties enforces the weak isospin breakdown. 
Heinrich Saller (MPI f. Physik)