Conformal Inflation, Modulated Reheating, and WMAP5

TL;DR

This paper explores how conformal inflation models with modulated reheating produce distinctive density perturbations, potentially distinguishable from standard models, and compares theoretical predictions with WMAP5 observational data.

Contribution

It introduces a detailed analysis of density perturbations in conformal inflation with modulated reheating, highlighting the impact of non-minimal coupling and observational constraints.

Findings

Large running of the spectral index predicted

Deviations from exact conformal coupling modify fluctuations

WMAP5 data favor a blue tilted spectrum in this model

Abstract

We investigate density perturbations generated through modulated reheating while inflation is driven by a conformally coupled scalar field. A large running of the spectral index is obtained, which reflects the basic nature of conformal inflation that higher-order time derivatives of the Hubble parameter during inflation are not necessarily small. This feature may allow us to distinguish between conformal inflation models and standard minimally coupled ones. We also investigate how the resulting fluctuations are modified when there is a deviation from an exact conformal coupling between the inflaton and gravity. Finally, we apply our results to the warped brane inflation model and see that observational bounds from the WMAP5 data suggest a blue tilted density perturbation spectrum.