Quintessence-dominated cyclic universe with negative cosmological constant.
Saved in:
| Title: | Quintessence-dominated cyclic universe with negative cosmological constant. |
|---|---|
| Authors: | Ahmed, Nasr1 (AUTHOR) nasr.ahmed@nriag.sci.eg, Bamba, Kazuharu2 (AUTHOR) bamba@sss.fukushima-u.ac.jp |
| Source: | European Physical Journal C -- Particles & Fields. May2026, Vol. 86 Issue 5, p1-13. 13p. |
| Subjects: | Cosmological constant, Energy density, Dark energy, Physical cosmology, Expanding universe |
| Abstract: | We investigate two simplified non-singular cyclic models with a negative time-varying cosmological constant to represent the non-conventional mechanism of negative cosmological constant expected to address the late-time cosmic acceleration. We show that a physically acceptable evolution with positive energy density can be realized, while negative energy density dominates in case of a positive or zero cosmological constant. In the first model, we demonstrate a sign flipping of the cosmic pressure in a quintessence-dominated universe with no violation of the null energy condition. In the second model, we propose a matter-bounce scenario with showing the crossing of the phantom divide line in the vicinity of the bounce. We find that while we get positive kinetic term and scalar potential, the sum of scalar and quantum potentials is negative. [ABSTRACT FROM AUTHOR] |
| Copyright of European Physical Journal C -- Particles & Fields is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
|
Full text is not displayed to guests.
Login for full access.
|
|
| Abstract: | We investigate two simplified non-singular cyclic models with a negative time-varying cosmological constant to represent the non-conventional mechanism of negative cosmological constant expected to address the late-time cosmic acceleration. We show that a physically acceptable evolution with positive energy density can be realized, while negative energy density dominates in case of a positive or zero cosmological constant. In the first model, we demonstrate a sign flipping of the cosmic pressure in a quintessence-dominated universe with no violation of the null energy condition. In the second model, we propose a matter-bounce scenario with showing the crossing of the phantom divide line in the vicinity of the bounce. We find that while we get positive kinetic term and scalar potential, the sum of scalar and quantum potentials is negative. [ABSTRACT FROM AUTHOR] |
|---|---|
| ISSN: | 14346044 |
| DOI: | 10.1140/epjc/s10052-026-15765-2 |
