### Abstract

A modified-gravity theory is considered with a four-form 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 four-form amplitude F and allows for a study of its dynamics. The theory gives a flat Friedmann-Robertson-Walker 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 near-critical 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 so-called cold dark matter in the standard Friedmann-Robertson-Walker framework.

Original language | English |
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Article number | 063528 |

Pages (from-to) | 1-12 |

Journal | Physical Review D |

Volume | 78 |

Issue number | 6 |

DOIs | |

Publication status | Published - 2008 |

MoE publication type | A1 Journal article-refereed |

### Keywords

- dynamic vacuum
- modofied gravity theory

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## Cite this

Klinkhamer, F., & Volovik, G. (2008). Dynamic vacuum variable and equilibrium approach in cosmology.

*Physical Review D*,*78*(6), 1-12. [063528]. https://doi.org/10.1103/PhysRevD.78.063528