This paper presents a minimal scalar–tensor extension of General Relativity consisting of a single real scalar field non-minimally coupled to curvature, introducing only two parameters: scalar mass mϕ and dimensionless coupling α. The full field equations are derived, weak-field and cosmological limits analyzed, and stability checked. Observational constraints are discussed, including solar system tests, cosmological equation-of-state deviations, structure growth rate, and possible scalar gravitational wave polarization. The model is mathematically consistent, minimal, and falsifiable.
Myomin Aung (Thu,) studied this question.