Gravitation and the new improved energy‐momentum tensor

We give precise definitions of the weak and strong principles of equivalence and show that the new gravitational theory based on the improved energy‐momentum tensor of Callan, Coleman, and Jackiw [Ann. Phys. (N.Y.) 59, 42 (1970)] satisfies both of these principles. As a consequence of the equality between the 4‐momentum given by the canonical energy‐momentum tensor and the ``momentum'' given by the pseudotensor that is the source of gravitation, the weak principle is also shown to hold in more general Einstein theories. Investigation of the interactions of a scalar field in the new gravitational theory shows that, besides the familiar long range interaction, there exists a new short range gravitational interaction between any scalar field and other matter.