1 Brane collisions and braneworld cosmology

Recently, we proposed a new braneworld model 1) in which the collision of a brane universe and a vacuum bubble coming from the extra-dimension is utilized as a trigger of brane big-bang. In this article, mainly reviewing this model, we briefly summarize cosmological braneworld scenarios in which collision of branes plays an important role. Braneworld scenario especially of the Randall-Sundrum type 2) have recently attracted much attention. In particular, cosmological models in this scenario have been studied actively 3), 4). It has been shown that braneworld cosmology seems to be consistent with the 4-dimensional conventional cosmology at least on scales much