Born-Again Braneworld

We propose a cosmological braneworld scenario in which two branes collide and emerge as reborn branes with signs of tensions opposite to the original tensions of respective branes. In this scenario, the branes are assumed to be inflating. However, the whole dynamics is different from the usual inflation due to the non-trivial dynamics of the radion field. Transforming the conformal frame to the Einstein frame, this born-again scenario resembles the pre-big-bang scenario. Thus our scenario has features of both inflation and pre-big-bang scenarios. In particular, the gravitational waves produced from vacuum fluctuations will have a very blue spectrum, while the inflaton field will give rise to a standard scale-invariant spectrum.