Modified gravity with arbitrary coupling between matter and geometry

Abstract

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.

12 pages, no figures, accepted for publication in PLB. Some further references added

References in corpus (29)

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Cited by in corpus (4)

• Initial and final de Sitter universes from modified $f(R)$ gravity
• Gödel-type universes in f(R) gravity
• Motion of test bodies in theories with nonminimal coupling
• Implications of non-analytical f(R) gravity at Solar-System scales