Braneworld Flux Inflation

TL;DR

This paper introduces a 5-dimensional brane inflation model driven by flux and collision dynamics, with unique fluctuation spectra, offering a novel approach to early universe cosmology.

Contribution

It presents a geometrical brane inflation model with flux-driven acceleration and collision-induced termination, incorporating a curvaton mechanism for density perturbations.

Findings

Radion field fluctuations have a steeply tilted, red spectrum.

Primordial gravitational waves have a flat spectrum.

Density perturbations may originate from a curvaton mechanism.

Abstract

We propose a geometrical model of brane inflation where inflation is driven by the flux generated by opposing brane charges and terminated by the collision of the branes, with charge annihilation. We assume the collision process is completely inelastic and the kinetic energy is transformed into the thermal energy after collision. Thereafter the two branes coalesce together and behave as a single brane universe with zero effective cosmological constant. In the Einstein frame, the 4-dimensional effective theory changes abruptly at the collision point. Therefore, our inflationary model is necessarily 5-dimensional in nature. As the collision process has no singularity in 5-dimensional gravity, we can follow the evolution of fluctuations during the whole history of the universe. It turns out that the radion field fluctuations have a steeply tilted, red spectrum, while the primordial gravitational waves have a flat spectrum. Instead, primordial density perturbations could be generated by a curvaton mechanism.