### 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}lm^{2} ≪ 1, where l̄ is the curvature radius of the effectively anti-de Sitter bulk, but it is violated if |l̄m ^{2}lm^{2}, 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}l̄^{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}|l̄^{2} is large.

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

Article number | 024014 |

Journal | Physical Review D |

Volume | 65 |

Issue number | 2 |

DOIs | |

Publication status | Published - 2002 |

### All Science Journal Classification (ASJC) codes

- Physics and Astronomy (miscellaneous)

## Fingerprint Dive into the research topics of 'Quantum fluctuations in brane-world inflation without an inflaton on the brane'. Together they form a unique fingerprint.

## Cite this

*Physical Review D*,

*65*(2), [024014]. https://doi.org/10.1103/PhysRevD.65.024014