Gauge-Higgs unification in the 5 dimensional E_6 and E_7 GUTs on   orbifold
  We consider 5 dimensional E_6 and E_7 supersymmetric grand unified theories (GUTs) on an orbifold S^1/Z_2, in which the Higgs fields arise from the 5th components of the 5D gauge fields. We introduce matter fields in 5 dimensions, then the Yukawa interactions are induced from the gauge interactions among the 5th component of gauge fields and the bulk hyper-multiplets. The adjoint and fundamental representations of bulk matter fields can induce all Yukawa interactions of the standard model in E_6 GUT. Furthermore, realistic fermion mass hierarchies and flavor mixings with the CP violating phase can be reproduced by introducing the 4D brane localized fields and their interactions. E_7 GUT can produce all Yukawa interactions by introducing only adjoint matter hyper-multiplet in the bulk. The charge quantization and anomaly free structure on the 4D wall are satisfactory in our models. 
Naoyuki Haba, Yasuhiro Shimizu