Electroweak Symmetry Breaking in Two Higgs Doublet Model from 6D Gauge-Higgs Unification on $T^2/Z_2$

Electroweak symmetry breaking is explored in a two Higgs doublet model based on a six dimensional $SU(4)$ gauge-Higgs unification compactified on an orbifold $T^2/Z_2$. The remarkable property of this model is a prediction of realistic weak mixing angle $\sin^2 \theta_W = 1/4$ at the compactification scale. We calculate one-loop effective potential of the Standard Model Higgs boson from the contributions of the gauge boson and the fermion in a four-rank totally symmetric tensor where top quark is included. We find that the electroweak symmetry breaking certainly takes place.