### Abstract

A Randall-Sundrum-type brane-cosmological model in which slow-roll inflation on the brane is driven solely by a bulk scalar field was recently proposed by Himemoto and Sasaki. We analyze their model in detail and calculate the quantum fluctuations of the bulk scalar field φ with m^{2} = V″(Φ). We decompose the bulk scalar field into the infinite mass spectrum of four-dimensional fields; the field with the smallest mass square, called the zero mode, and the Kaluza-Klein modes above it with a mass gap. We find the zero-mode dominance of the classical solution holds if |m^{2}|l̄^{2}≪1, where l̄ is the curvature radius of the effectively anti-de Sitter bulk, but it is violated if |m^{2}|l̄^{2}≫1, though the violation is very small. Then we evaluate the vacuum expectation value 〈δφ^{2}〉 on the brane. We find the zero-mode contribution completely dominates if |m^{2}|l^{-2}≪1, similar to the case of classical background. In contrast, we find the Kaluza-Klein contribution is small but non-negligible if the value of |m^{2}|l^{-2} is large.

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

Article number | 024014 |

Pages (from-to) | 240141-240149 |

Number of pages | 9 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 65 |

Issue number | 2 |

Publication status | Published - Jan 15 2002 |

Externally published | Yes |

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### All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*65*(2), 240141-240149. [024014].

**Quantum fluctuations in brane-world inflation without an inflaton on the brane.** / Sago, Norichika; Himemoto, Yoshiaki; Sasaki, Misao.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 65, no. 2, 024014, pp. 240141-240149.

}

TY - JOUR

T1 - Quantum fluctuations in brane-world inflation without an inflaton on the brane

AU - Sago, Norichika

AU - Himemoto, Yoshiaki

AU - Sasaki, Misao

PY - 2002/1/15

Y1 - 2002/1/15

N2 - A Randall-Sundrum-type brane-cosmological model in which slow-roll inflation on the brane is driven solely by a bulk scalar field was recently proposed by Himemoto and Sasaki. We analyze their model in detail and calculate the quantum fluctuations of the bulk scalar field φ with m2 = V″(Φ). We decompose the bulk scalar field into the infinite mass spectrum of four-dimensional fields; the field with the smallest mass square, called the zero mode, and the Kaluza-Klein modes above it with a mass gap. We find the zero-mode dominance of the classical solution holds if |m2|l̄2≪1, where l̄ is the curvature radius of the effectively anti-de Sitter bulk, but it is violated if |m2|l̄2≫1, though the violation is very small. Then we evaluate the vacuum expectation value 〈δφ2〉 on the brane. We find the zero-mode contribution completely dominates if |m2|l-2≪1, similar to the case of classical background. In contrast, we find the Kaluza-Klein contribution is small but non-negligible if the value of |m2|l-2 is large.

AB - A Randall-Sundrum-type brane-cosmological model in which slow-roll inflation on the brane is driven solely by a bulk scalar field was recently proposed by Himemoto and Sasaki. We analyze their model in detail and calculate the quantum fluctuations of the bulk scalar field φ with m2 = V″(Φ). We decompose the bulk scalar field into the infinite mass spectrum of four-dimensional fields; the field with the smallest mass square, called the zero mode, and the Kaluza-Klein modes above it with a mass gap. We find the zero-mode dominance of the classical solution holds if |m2|l̄2≪1, where l̄ is the curvature radius of the effectively anti-de Sitter bulk, but it is violated if |m2|l̄2≫1, though the violation is very small. Then we evaluate the vacuum expectation value 〈δφ2〉 on the brane. We find the zero-mode contribution completely dominates if |m2|l-2≪1, similar to the case of classical background. In contrast, we find the Kaluza-Klein contribution is small but non-negligible if the value of |m2|l-2 is large.

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M3 - Article

VL - 65

SP - 240141

EP - 240149

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 1550-7998

IS - 2

M1 - 024014

ER -