Gravity theories with non-minimally coupled scalar fields are used as characteristic examples in order to demonstrate the challenges, pitfalls and future perspectives of considering alternatives to general relativity. These lecture notes can be seen as an illustration of concepts, subtleties and techniques present in all alternative theories, but they also provide a brief review of generalised scalar-tensor theories.
Sotiriou, T. P. (2015). Modifications of Einstein’s Theory of Gravity at Large Distances (Vol. 892, p. 21). https://doi.org/10.1007/978-3-319-10070-8