Accidental Inflation from K\"ahler Uplifting

TL;DR

This paper explores string inflation models within the K"ahler uplifting framework, demonstrating that quantum corrections enable successful inflation with observable predictions like spectral index and tensor-to-scalar ratio.

Contribution

It introduces the concept of 'inflation by deflation' (IBD) in string theory, showing how quantum corrections allow for inflation models with specific observational signatures.

Findings

Models predict a red spectral index consistent with observations.

The 'inflation by deflation' scenario is insensitive to initial conditions.

Observable running and enhanced tensor-to-scalar ratio are achievable.

Abstract

We analyze the possibility of realizing inflation with a subsequent dS vacuum in the K\"ahler uplifting scenario. The inclusion of several quantum corrections to the 4d effective action evades previous no-go theorems and allows for construction of simple and successful models of string inflation. The predictions of several benchmark models are in accord with current observations, i.e., a red spectral index, negligible non-gaussianity, and spectral distortions similar to the simplest models of inflation. A particularly interesting subclass of models are "left-rolling" ones, where the overall volume of the compactified dimensions shrinks during inflation. We call this phenomenon "inflation by deflation" (IBD), where deflation refers to the internal manifold. This subclass has the appealing features of being insensitive to initial conditions, avoiding the overshooting problem, and allowing for observable running $\alpha$ ~ 0.012 and enhanced tensor-to-scalar ratio $r$ ~ $10^{-5}$. The latter results differ significantly from many string inflation models.