Constraints on scalar-tensor theories from observations
  We study the dynamical description of scalar-tensor gravity by performing the best-fit analysis for two cases of exponential and power-law form of the potential and scalar field function coupled to the curvature. The models are then tested against observational data. The results show that in both scenarios the Universe undergoes an acceleration expansion period and the geometrical equivalent of dark energy is associated with a time-dependent equation of state. 
Hossein Farajollahi, Amin Salehi, Mohammad Nasiri
gr-qc