An Einstein-like theory of gravity with a non-Newtonian weak-field limit

摘要

We propose a model describing Einstein gravity coupled to a scalar field with an exponential potential. We show that the weak-field limit of the model has static solutions given by a gravitational potential behaving for large distances as ln r. The Newtonian term GM/r appears only as subleading. Our model can be used to give a phenomenological explanation of the rotation Curves of the galaxies without postulating the presence of dark matter. This can be achieved only by giving up the Einstein equivalence principle at galactic scales.