### Abstract

We study collision of two domain walls in five-dimensional (5D) spacetime and creation of matter fields. This may provide the reheating mechanism in cosmological models based on a colliding-brane scenario such as the ekpyrotic (or cyclic) universe. We first analyze the dynamics of colliding domain walls both in 5D Minkowski back-ground spacetime and in asymptotic AdS spacetime including self-gravity. We find that multiple bounces appear at collision. In the case with gravity, we find that a spacelike curvature singularity is formed in the bulk, but it is covered by a horizon. Next we analyze production of particles at collision of two domain walls. For a scalar field, the energy density of created particles is evaluated as ρ ≈ 20_{g} ^{-4}N_{b} m_{φ}^{4} where ḡ is a coupling constant of particles to a domain-wall scalar field, N_{b} is the number of bounces at the collision and m_{φ} is a fundamental mass scale of the domain wall. We also study the behaviour of 5D fermions localized on domain walls, when two walls collide in a 5D Minkowski background spacetime. For k = 0 mode, we find that most fermions are localized on both branes as a whole even after collision. However, how much fermions are localized on which brane depends sensitively on the incident velocity and the coupling constants.

Original language | English |
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Pages (from-to) | 90-99 |

Number of pages | 10 |

Journal | Progress of Theoretical Physics Supplement |

Issue number | 172 |

DOIs | |

Publication status | Published - 2008 Jan 1 |

### ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)