“…Following recent development on extra dimension physics [22,27,32,36,43], the Scherk-Schwarz breaking [3,19,20,22,27] and Orbifold breaking [12,22,23,25,26,27] have opened the way for producing Higgs through the extra-dimensional compactification effect which induces the Higgs itself, and known as the gauge-Higgs boson unification [11,12,21,22,27]. Recently a grand gauge-Higgs unification based on 5D SU(6) compactified on an orbifold S 1 /Z 2 with fermions in two 6-plets and one 20-plet shows successful breaking with no proton decay at tree level but a little low compactification scale and heavy Higgs [8].…”