Slow Roll in Brane Inflation

TL;DR

This paper investigates the conditions for slow-roll inflation within string theory models, emphasizing the role of flat directions, shift symmetry, and contributions to the inflationary potential, supported by theoretical checks and transformations.

Contribution

It demonstrates how flat directions and slow-roll conditions naturally arise in string theory models of brane inflation through Kähler transformations and symmetry considerations.

Findings

Flat directions are expected in certain string compactifications.

Shift symmetry can facilitate slow-roll inflation.

Various contributions to the potential influence slow-roll viability.

Abstract

We address the issue of slow-roll in string theory models of inflation. Using a K\"{a}hler transformation and results from the D3-D7 model, we show why we expect flat directions to be present and slow-roll to be possible in general. We connect with earlier discussions of shift symmetry for $T^6/Z_2$ and $K3\times T^2/Z_2$ compactifications. We also collect various contributions to the inflationary potential and discuss their importance for slow-roll. We include a few simple checks of the form of the Kahler potential on $T^6/Z_2$ using T-duality.