A generalization to the Rastall theory and cosmic eras
Abstract
A generalized version for the Rastall theory is proposed showing the agreement with the cosmic accelerating expansion. In this regard, a coupling between geometry and the pressureless matter fields is derived which may play the role of dark energy, responsible for the current accelerating expansion phase. Moreover, our study also shows that the radiation field may not be coupled to the geometry in a nonminimal way which represents that the ordinary energymomentum conservation law is respected by the radiation source. It is also shown that the primary inflationary era may be justified by the ability of the geometry to couple to the energymomentum source in an empty flat FRW universe. In fact, this ability is independent of the existence of the energymomentum source and may compel the empty flat FRW universe to expand exponentially. Finally, we consider a flat FRW universe field by a spatially homogeneous scalar field evolving in potential V(φ ), and study the results of applying the slowroll approximation to the system which may lead to an inflationary phase for the universe expansion.
 Publication:

European Physical Journal C
 Pub Date:
 April 2017
 DOI:
 10.1140/epjc/s100520174811z
 arXiv:
 arXiv:1704.02458
 Bibcode:
 2017EPJC...77..259M
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Theory
 EPrint:
 11 pages