Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Chiral 4d string vacua with D-branes and NSNS and RR fluxes

Juan F. G. Cascales, Angel M. Uranga

TL;DR

This work constructs chiral four-dimensional string vacua by combining D-branes with NSNS and RR 3-form fluxes in type IIB orientifolds, using magnetised D9-branes on $T^6/(\mathbb{Z}_2\times\mathbb{Z}_2)$ to generate chiral spectra while stabilizing most moduli through fluxes. The authors analyze consistency conditions, SUSY preservation, and anomaly cancellation, providing explicit models with supersymmetric subsectors and even a non-supersymmetric SU(5) example, all while ensuring RR tadpole cancellation. A key insight is that fluxes stabilize complex structure and many Kahler moduli, and the magnetised-brane setup yields tractable chiral spectra; the framework also maps, under T-duality, to D8-branes on non-Calabi-Yau half-flat geometries with metric fluxes. Discrete B-fields and dual descriptions further enrich model-building options, including RR-tadpole reshaping and new Wess-Zumino couplings, suggesting a versatile path toward realistic string vacua with stabilized moduli and chiral matter.

Abstract

We discuss type IIB orientifolds with D-branes, and NSNS and RR field strength fluxes. The D-brane sectors lead 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. We describe the construction of N=1 supersymmetric models in the context of orientifolds of IIB theory on T^6/Z_2 x Z_2, containing D9-branes with world-volume magnetic fluxes, and illustrate model building possibilities with several explicit examples. We comment on a T-dual picture with D8-branes on non-Calabi-Yau half-flat geometries, and discuss some of the topological properties of such configurations. We also explore the construction of models with fluxes and with D3-branes at singularities and present a non-supersymmetric 3-family SU(5) model.

Chiral 4d string vacua with D-branes and NSNS and RR fluxes

TL;DR

This work constructs chiral four-dimensional string vacua by combining D-branes with NSNS and RR 3-form fluxes in type IIB orientifolds, using magnetised D9-branes on to generate chiral spectra while stabilizing most moduli through fluxes. The authors analyze consistency conditions, SUSY preservation, and anomaly cancellation, providing explicit models with supersymmetric subsectors and even a non-supersymmetric SU(5) example, all while ensuring RR tadpole cancellation. A key insight is that fluxes stabilize complex structure and many Kahler moduli, and the magnetised-brane setup yields tractable chiral spectra; the framework also maps, under T-duality, to D8-branes on non-Calabi-Yau half-flat geometries with metric fluxes. Discrete B-fields and dual descriptions further enrich model-building options, including RR-tadpole reshaping and new Wess-Zumino couplings, suggesting a versatile path toward realistic string vacua with stabilized moduli and chiral matter.

Abstract

We discuss type IIB orientifolds with D-branes, and NSNS and RR field strength fluxes. The D-brane sectors lead 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. We describe the construction of N=1 supersymmetric models in the context of orientifolds of IIB theory on T^6/Z_2 x Z_2, containing D9-branes with world-volume magnetic fluxes, and illustrate model building possibilities with several explicit examples. We comment on a T-dual picture with D8-branes on non-Calabi-Yau half-flat geometries, and discuss some of the topological properties of such configurations. We also explore the construction of models with fluxes and with D3-branes at singularities and present a non-supersymmetric 3-family SU(5) model.

Paper Structure

This paper contains 26 sections, 81 equations, 2 figures, 4 tables.

Table of Contents

  1. Introduction
  2. The $\bf T^6/(\bf Z_2\times\bf Z_2)$ orbifold
  3. Review of fluxes
  4. Consistency conditions and moduli stabilization
  5. Supersymmetry
  6. Fluxes in the $\bf T^6/(\bf Z_2\times \bf Z_2)$
  7. Philosophy of our approach
  8. Magnetised D-branes
  9. Magnetised D-branes in toroidal compactifications
  10. Magnetised D-branes in toroidal orientifolds
  11. Magnetised D-branes in the $\bf T^6/(\bf Z_2\times\bf Z_2)$ orbifold
  12. The models
  13. Construction of the models
  14. The spectrum
  15. Anomaly cancellation
  16. ...and 11 more sections

Figures (2)

  • Figure 1: A D$p$-brane ending on a D$(p+2)$-brane with volume along some component of $H_3$. This represents a consistent way of wrapping a D$(p+2)$-brane on a cycles with non-zero $H_3$ flux, or a process mediating the decay of a D$p$-brane wrapped on a homologically non-trivial cycle $W$.
  • Figure 2: A system D8 - (anti-D8)-branes with volume along some component of $H_3$ is consistent if there are additional D6-branes starting and ending on them. The T-dual version is that a system of D9 - (anti-D9)-branes with volume along some component of $H_3$ is consistent if additional fractional D5-branes are present.