Orbifold GUT model with nine Higgs doublets
  We describe a non-supersymmetric orbifold GUT based on SU(5) symmetry. It is a modification of Kawamura's 5-D orbifold GUT model. The difference lies in the choice of Higgs scalars as we have allowed only 5-plets of SU(5) in the GUT scale. This variant was originally proposed by Brahmachari and Raychoudhuri. Proton decay problem and the doublet triplet splitting problems are solved by extra dimensional mechanism. The unification scale is around $5.0 \times 10^{13}$ GeVs. In low energy there are nine Higgs doublets. One at the 100 GeV region and eight others degenerate at around 1.4 TeV. It is an attractive non-supersymmetric extension of standard model with very rich collider physics phenomenology. 
Biswajoy Brahmachari