Dynamics and perturbations in assisted chaotic inflation

TL;DR

This paper studies assisted inflation driven by multiple scalar fields from higher-dimensional theories, highlighting how initial conditions influence late-time dynamics and density perturbations.

Contribution

It provides a detailed analysis of assisted inflation dynamics, emphasizing the persistence of initial condition effects on density perturbations.

Findings

Decoupling of fields from slow-roll regime analyzed

Late-time dynamics depend on initial conditions

Density perturbations retain memory of initial states

Abstract

On compactification from higher dimensions, a single free massive scalar field gives rise to a set of effective four-dimensional scalar fields, each with a different mass. These can cooperate to drive a period of inflation known as assisted inflation. We analyze the dynamics of the simplest implementation of this idea, paying particular attention to the decoupling of fields from the slow-roll regime as inflation proceeds. Unlike normal models of inflation, the dynamics does not become independent of the initial conditions at late times. In particular, we estimate the density perturbations obtained, which retain a memory of the initial conditions even though a homogeneous, spatially-flat Universe is generated.