The effective action of D-branes in Calabi-Yau orientifold compactifications

TL;DR

This review explores the effective actions of D-branes in Calabi-Yau orientifold compactifications, detailing the derivation of low-energy spectra, supergravity actions, and supersymmetry breaking mechanisms in type IIB string theory.

Contribution

It provides a comprehensive derivation of the low-energy effective supergravity actions for D3- and D7-branes in Calabi-Yau orientifolds, including flux-induced supersymmetry breaking effects.

Findings

Derived the massless spectrum for D3- and D7-branes

Computed soft supersymmetry breaking terms from fluxes

Analyzed the geometric structure related to N=1 special geometry

Abstract

In this review article we study type IIB superstring compactifications in the presence of space-time filling D-branes while preserving N=1 supersymmetry in the effective four-dimensional theory. This amount of unbroken supersymmetry and the requirement to fulfill the consistency conditions imposed by the space-time filling D-branes lead to Calabi-Yau orientifold compactifications. For a generic Calabi-Yau orientifold theory with space-time filling D3- or D7-branes we derive the low-energy spectrum. In a second step we compute the effective N=1 supergravity action which describes in the low-energy regime the massless open and closed string modes of the underlying type IIB Calabi-Yau orientifold string theory. These N=1 supergravity theories are analyzed and in particular spontaneous supersymmetry breaking induced by non-trivial background fluxes is studied. For D3-brane scenarios we compute soft-supersymmetry breaking terms resulting from bulk background fluxes whereas for D7-brane systems we investigate the structure of D- and F-terms originating from worldvolume D7-brane background fluxes. Finally we relate the geometric structure of D7-brane Calabi-Yau orientifold compactifications to N=1 special geometry.