2008/10/25 by T. Harko · 2 citations
Physics and Astronomy · #gr-qc #astro-ph #hep-th
paper · pdf · doi:10.1016/j.physletb.2008.10.007
published as Phys.Lett.B669:376-379,2008 · 12 pages, no figures, accepted for publication in PLB. Some further references added
arxiv created 2008/10/25 · arxiv updated 2009/12/01
The field equations of a generalized f(R) type gravity model, in which there is an arbitrary coupling between matter and geometry, are obtained. The equations of motion for test particles are derived from a variational principle in the particular case in which the Lagrange density of the matter is an arbitrary function of the energy-density of the matter only. Generally, the motion is non-geodesic, and takes place in the presence of an extra force orthogonal to the four-velocity. The Newtonian limit of the model is also considered. The perihelion precession of an elliptical planetary orbit in the presence of an extra force is obtained in a general form, and the magnitude of the extra gravitational effects is constrained in the case of a constant extra force by using Solar System observations.