Brane/Flux Interactions in Orientifolds

TL;DR

This paper derives the full bosonic Lagrangian for a supersymmetric string model with D3-branes and fluxes, demonstrating the consistency of approximation methods used in string compactifications.

Contribution

It provides the first complete derivation of the effective action for a D3-brane system with fluxes in an orientifold, confirming the validity of the dimensional reduction and T-duality approach.

Findings

Derived the full bosonic Lagrangian for the model.

Confirmed agreement with gauged supergravity results.

Supported the consistency of the approximation scheme.

Abstract

Combining the benefits of D-branes and background fluxes in string compactifications opens up the possibility to explore phenomenologically interesting brane world models with stabilized moduli. However, it is difficult to determine interaction effects among open strings and fluxes in the effective action. We derive the full bosonic Lagrangian of a (spontaneously broken) N=4 supersymmetric model with D3-branes and NSNS and RR 3-form fluxes in an orientifold of type IIB, that, without fluxes, would be T-dual to type I theory. In the limit where backreaction in form of a warp factor is neglected, the effective action can be obtained through a procedure that combines dimensional reduction and T-duality, and it is found to be in agreement with results from gauged supergravity. This provides evidence for the consistency of this commonly used approximation scheme.