Hybrid inflation and waterfall field in string theory from D7-branes

TL;DR

This paper constructs a string theory model of cosmological inflation using magnetised D7-branes, where the inflaton is the volume modulus and inflation ends via waterfall fields leading to a universe consistent with current observations.

Contribution

It provides an explicit string theory realization of hybrid inflation with a metastable de Sitter vacuum and waterfall fields within type IIB flux compactifications.

Findings

Inflation occurs near a metastable de Sitter vacuum.

Waterfall fields trigger the end of inflation and transition to a global minimum.

The model allows for a tunable vacuum energy compatible with the current universe.

Abstract

We present an explicit string realisation of a cosmological inflationary scenario we proposed recently within the framework of type IIB flux compactifications in the presence of three magnetised D7-brane stacks. Inflation takes place around a metastable de Sitter vacuum. The inflaton is identified with the volume modulus and has a potential with a very shallow minimum near the maximum. Inflation ends due to the presence of "waterfall" fields that drive the evolution of the Universe from a nearby saddle point towards a global minimum with tuneable vacuum energy describing the present state of our Universe.