### Abstract

We study gravitational theories with a cosmological constant and the Gauss-Bonnet curvature squared term and analyze the possibility of de Sitter expanding spacetime with a constant internal space. We find that there are two branches of the de Sitter solutions: both the curvature of the internal space and the cosmological constant are (1) positive and (2) negative. From the stability analysis, we show that the de Sitter solution of the case (1) is unstable, while that in the case (2) is stable. Namely de Sitter solution in the present system is stable if the cosmological constant is negative. We extend our analysis to the gravitational theories with higher-order Lovelock curvature terms. Although the existence and the stability of the de Sitter solutions are very complicated and highly depend on the coupling constants, there exist stable de Sitter solutions similar to the case (2). We also find de Sitter solutions with Hubble scale much smaller than the scale of a cosmological constant, which may explain a discrepancy between an inflation energy scale and the Planck scale.

Original language | English |
---|---|

Article number | 095 |

Journal | Journal of High Energy Physics |

Volume | 2014 |

Issue number | 6 |

DOIs | |

Publication status | Published - 2014 |

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### Keywords

- Classical Theories of Gravity
- Cosmology of Theories beyond the SM
- Supergravity Models
- Superstrings and Heterotic Strings

### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Journal of High Energy Physics*,

*2014*(6), [095]. https://doi.org/10.1007/JHEP06(2014)095

**Cosmic acceleration with a negative cosmological constant in higher dimensions.** / Maeda, Keiichi; Ohta, Nobuyoshi.

Research output: Contribution to journal › Article

*Journal of High Energy Physics*, vol. 2014, no. 6, 095. https://doi.org/10.1007/JHEP06(2014)095

}

TY - JOUR

T1 - Cosmic acceleration with a negative cosmological constant in higher dimensions

AU - Maeda, Keiichi

AU - Ohta, Nobuyoshi

PY - 2014

Y1 - 2014

N2 - We study gravitational theories with a cosmological constant and the Gauss-Bonnet curvature squared term and analyze the possibility of de Sitter expanding spacetime with a constant internal space. We find that there are two branches of the de Sitter solutions: both the curvature of the internal space and the cosmological constant are (1) positive and (2) negative. From the stability analysis, we show that the de Sitter solution of the case (1) is unstable, while that in the case (2) is stable. Namely de Sitter solution in the present system is stable if the cosmological constant is negative. We extend our analysis to the gravitational theories with higher-order Lovelock curvature terms. Although the existence and the stability of the de Sitter solutions are very complicated and highly depend on the coupling constants, there exist stable de Sitter solutions similar to the case (2). We also find de Sitter solutions with Hubble scale much smaller than the scale of a cosmological constant, which may explain a discrepancy between an inflation energy scale and the Planck scale.

AB - We study gravitational theories with a cosmological constant and the Gauss-Bonnet curvature squared term and analyze the possibility of de Sitter expanding spacetime with a constant internal space. We find that there are two branches of the de Sitter solutions: both the curvature of the internal space and the cosmological constant are (1) positive and (2) negative. From the stability analysis, we show that the de Sitter solution of the case (1) is unstable, while that in the case (2) is stable. Namely de Sitter solution in the present system is stable if the cosmological constant is negative. We extend our analysis to the gravitational theories with higher-order Lovelock curvature terms. Although the existence and the stability of the de Sitter solutions are very complicated and highly depend on the coupling constants, there exist stable de Sitter solutions similar to the case (2). We also find de Sitter solutions with Hubble scale much smaller than the scale of a cosmological constant, which may explain a discrepancy between an inflation energy scale and the Planck scale.

KW - Classical Theories of Gravity

KW - Cosmology of Theories beyond the SM

KW - Supergravity Models

KW - Superstrings and Heterotic Strings

UR - http://www.scopus.com/inward/record.url?scp=84904360649&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84904360649&partnerID=8YFLogxK

U2 - 10.1007/JHEP06(2014)095

DO - 10.1007/JHEP06(2014)095

M3 - Article

VL - 2014

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

SN - 1126-6708

IS - 6

M1 - 095

ER -