Dynamic vacuum variable and equilibrium approach in cosmology
Abstract
A modifiedgravity theory is considered with a fourform field strength F, a variable gravitational coupling parameter G(F), and a standard matter action. This theory provides a concrete realization of the general vacuum variable q as the fourform amplitude F and allows for a study of its dynamics. The theory gives a flat FriedmannRobertsonWalker universe with rapid oscillations of the effective vacuum energy density (cosmological “constant”), whose amplitude drops to zero asymptotically. Extrapolating to the present age of the Universe, the order of magnitude of the average vacuum energy density agrees with the observed nearcritical vacuum energy density of the present universe. It may even be that this type of oscillating vacuum energy density constitutes a significant part of the socalled cold dark matter in the standard FriedmannRobertsonWalker framework.
 Publication:

Physical Review D
 Pub Date:
 September 2008
 DOI:
 10.1103/PhysRevD.78.063528
 arXiv:
 arXiv:0806.2805
 Bibcode:
 2008PhRvD..78f3528K
 Keywords:

 98.80.Jk;
 04.20.Cv;
 95.35.+d;
 95.36.+x;
 Mathematical and relativistic aspects of cosmology;
 Fundamental problems and general formalism;
 Dark matter;
 Dark energy;
 General Relativity and Quantum Cosmology;
 Astrophysics;
 High Energy Physics  Theory
 EPrint:
 24 (not 25) pages, v7(=v6 with latex problem corrected): published version in preprint style