Parallel Transport in Gauge Theory on $M_4 \times Z_2$ Geometry
  We apply the gauge theory on $M_4\times Z_2$ geometry previously proposed by Konisi and Saito to the Weinberg-Salam model for electroweak interactions, especially in order to clarify the geometrical meaning of curvatures in this geometry. Considering the Higgs field to be a gauge field along $Z_2$ direction, we also discuss the BRST invariant gauge fixing in this theory. 
Takesi Saito, Kunihiko Uehara