D-branes, axion monodromy and large-field inflation

Abstract

This thesis explores different realizations of large-field inflation in type II string theory compactifications, in presence of the open-string sector, within the context of axion monodromy. Such models, which are described by the DBI action for large vevs of the inflaton candidate, are explicit realizations of F-term axion monodromy. From their supergravity description we study aspects about moduli stabilization and backreaction of the closed-string sector. First of all, we propose a model in type IIA where the inflationary potential is generated by a D6-brane wrapping a three-cycle satisfying a certain topological condition. Afterwards, we explore in the context of typeIIB/F-theory flux compactifications with mobile D7-branes a new flattening effect, dubbed flux flattening, which is observed on the DBI+CS action in presence of the most generic flux background. Finally, we explore the possibility of embedding ’stabilizer’ fields in type II string theory compactifications and analyze the possibility of transplacnkian field ranges in several examples consistent with moduli stabilization and backreaction.