Abstract We propose a unified model for the three Standard Model (SM) gauge symmetries and SU(3) family symmetry based on SO(16) grand unified gauge symmetry on six-dimensional (6D) spacetime. In this model, three chiral generations of quarks and leptons are unified into a 6D Weyl fermion in the spinor representation of SO(16). The 6D SO(16) gauge anomaly is canceled by the vectorlike nature of the model, and the 4D gauge anomalies are canceled by introducing suitable 4D localized fermions at the fixed point. The 4D gauge coupling constant of SO(16) has the property of becoming weaker at high energies.
Chiang et al. (Tue,) studied this question.