Chiral 4d String Vacua with D-branes and Moduli Stabilization

TL;DR

The paper develops a framework to realize chiral four-dimensional string vacua with moduli stabilization by combining Type IIB orientifolds, D-branes, and NSNS/RR fluxes. It presents two concrete classes—D3-branes at singularities and magnetised D9-branes on $T^6$ and orbifolds—demonstrating how closed-string fluxes stabilize dilaton and complex structure while preserving or yielding chiral open-string sectors. Explicit models include a 3-family SU(5) GUT from D3-branes at a $f C^3/f Z_3$ singularity in flux backgrounds and Standard Model–like spectra from magnetised branes with flux, in toroidal orientifolds. The work explores both supersymmetric and non-supersymmetric combinations, discusses tadpole and consistency constraints, and outlines future directions toward moduli stabilization, de Sitter constructions, and a landscape of realistic vacua. Overall, it provides concrete techniques and examples linking moduli stabilization with realistic chiral gauge sectors in string theory.

Abstract

We discuss type IIB orientifolds with D-branes, and NSNS and RR field strength fluxes, with D-brane sectors leading to open string spectra with non-abelian gauge symmetry and charged chiral fermions. The closed string field strengths generate a scalar potential stabilizing most moduli. Hence the models combine the advantages of leading to phenomenologically interesting (and even semirealistic) chiral open string spectra, and of stabilizing the dilaton and most geometric moduli. We describe the explicit construction of two classes of non-supersymmetric models on $\IT^6$ and orbifolds/orientifolds thereof, with chiral gauge sector arising from configurations of D3-branes at singularities, and from D9-branes with non-trivial world-volume magnetic fields. The latter examples yield the chiral spectrum of just the Standard Model.