On phenomenological three graviton vertex

In General Relativity Theory the graviton interacts in 3-graviton vertex with a tensor which is not an energy-momentum tensor of gravitational field. The possibility is considered that graviton interacts with some definite gravitational energy-momentum tensor. This tensor in a gauge, which excludes nonphysical degrees of freedom, is remarkable in that it gives gravitational energy density for the Newtonian center in the same manner as the electromagnetic energy-momentum tensor does for the Coulomb center. In the S-matrix approach used here the external gravitational field has only a subsidiary role similar to that of the external field in quantum electrodynamics