Confronting K\"ahler moduli inflation with CMB data

TL;DR

This paper investigates how string theory-inspired Kähler moduli inflation models are affected by post-inflationary epochs dominated by moduli particles, impacting inflationary predictions and their consistency with recent CMB data.

Contribution

It provides a numerical analysis of Kähler moduli inflation considering post-inflationary effects, linking model parameters to observable inflationary quantities using current data.

Findings

Post-inflationary moduli domination modifies the number of e-foldings.

Model parameters influence inflationary observables significantly.

Current data constrains the parameter space of Kähler moduli inflation.

Abstract

In models of inflation obtained from string compactification, moduli vacuum misalignment leads to an epoch in the post-inflationary history of the universe when the energy density is dominated by cold moduli particles. This effect leads to a modification in the number of $e$-foldings ($N_{\rm pivot}$) between horizon exit of the CMB modes and the end of inflation. Taking K\"ahler moduli inflation as a prototype, the shift in $e$-foldings turns out to be a function of the model parameters which also determines the inflationary observables. We analyse this scenario numerically using publicly available {\sc{ModeChord}} and {\sc{CosmoMC}} with the latest \emph{Planck+BICEP2/Keck array} data to constrain the model parameters and $N_{\rm pivot}$. In light of the present and future precision data, the results show the importance of careful consideration of any post-inflationary non-standard epoch, as well as of the effects of reheating.