Born-Again Braneworld

TL;DR

This paper introduces a novel cosmological braneworld model where colliding and reborn branes with opposite tensions lead to unique inflationary dynamics, producing distinctive gravitational wave spectra and combining features of inflation and pre-big-bang scenarios.

Contribution

It presents a new braneworld scenario involving brane collisions and rebirth, with a detailed analysis of its inflationary dynamics and gravitational wave predictions.

Findings

Reborn branes have opposite tensions after collision.

The scenario produces a very blue gravitational wave spectrum.

The inflaton yields a standard scale-invariant spectrum.

Abstract

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.