Grand Unified Theory based on the SU(6) symmetry
  We present a complete set of generators for the rank 5 special unitary group, SU(6), to unify strong, weak and electromagnetic interactions. The unification is realized through the breaking pattern of SU)6) -> SU(3)_C x SU(3)_H x U(1)_C followed by SU(3)_H -> SU(2)_L x U(1)_B. All known elementary particles and its quantum numbers are well accomodated in its {6} and {15} multiplets. These multiplets require a new neutral fermion which should be assigned as the heavy Majorana neutrino to realize the seesaw mechanism naturally in the minimal scenario of this model. 
A. Hartanto (UI) and L.T. Handoko (LIPI, UI)