Brans-Dicke theory with the cosmological constant from M_4 x Z_2   geometry
  The theory on M_4 x Z_2 geometry is applied to the Einstein gravity to yield the Brans-Dicke theory on M_4 geometry. The geometrical meaning and the relation between the curvatures and the torsions are clarified. The cosmological constant is also introduced into the pure Einstein action on M_4 x Z_2 in order to determine the explicit form of the cosmological term in the Brans-Dicke theory on M_4 geometry. 
Kunihiko Uehara