Brane Inflation and Cosmic String Tension in Superstring Theory

TL;DR

This paper reanalyzes brane inflation in superstring theory, showing that moderate tuning suffices for slow roll conditions and that cosmic string tension can be high enough to be observable, providing a potential window into fundamental physics.

Contribution

It demonstrates that the slow roll condition in brane inflation requires only moderate tuning and highlights the sensitivity of cosmic string tension to conformal coupling, enhancing prospects for detection.

Findings

Moderate tuning suffices for slow roll in brane inflation.

Cosmic string tension can reach observational bounds with less fine-tuning.

Multi-throat scenarios improve chances of cosmic string detection.

Abstract

In a simple reanalysis of the KKLMMT scenario, we argue that the slow roll condition in the D3-anti-D3-brane inflationary scenario in superstring theory requires no more than a moderate tuning. The cosmic string tension is very sensitive to the conformal coupling: with less fine-tuning, the cosmic string tension (as well as the ratio of tensor to scalar perturbation mode) increases rapidly and can easily saturate the present observational bound. In a multi-throat brane inflationary scenario, this feature substantially improves the chance of detecting and measuring the properties of the cosmic strings as a window to the superstring theory and our pre-inflationary universe.