Inflating in a Better Racetrack

TL;DR

This paper develops a string theory-based racetrack inflation model using explicit Calabi-Yau compactification, stabilizing moduli with fluxes and nonperturbative effects, and identifies conditions for inflation consistent with observational data.

Contribution

It introduces a new racetrack inflation scenario based on explicit type IIB compactification with stabilized moduli and a calculable superpotential, advancing string cosmology models.

Findings

Inflation starts at a saddle point and proceeds via eternal topological inflation.

The model predicts a spectral index n_s = 0.95, consistent with observations.

The inflationary scale is approximately 3 x 10^{14} GeV.

Abstract

We present a new version of our racetrack inflation scenario which, unlike our original proposal, is based on an explicit compactification of type IIB string theory: the Calabi-Yau manifold P^4_[1,1,1,6,9]. The axion-dilaton and all complex structure moduli are stabilized by fluxes. The remaining 2 Kahler moduli are stabilized by a nonperturbative superpotential, which has been explicitly computed. For this model we identify situations for which a linear combination of the axionic parts of the two Kahler moduli acts as an inflaton. As in our previous scenario, inflation begins at a saddle point of the scalar potential and proceeds as an eternal topological inflation. For a certain range of inflationary parameters, we obtain the COBE-normalized spectrum of metric perturbations and an inflationary scale of M = 3 x 10^{14} GeV. We discuss possible changes of parameters of our model and argue that anthropic considerations favor those parameters that lead to a nearly flat spectrum of inflationary perturbations, which in our case is characterized by the spectral index n_s = 0.95.