Toward Realistic Intersecting D-Brane Models

TL;DR

This article surveys intersecting D-brane models in Type II orientifolds as a geometric framework to realize chiral gauge theories with gravity. It covers the construction rules (tadpole cancellation, supersymmetry via sLag cycles, Green-Schwarz anomaly cancellation), explicit toroidal and orbifold examples, and the emergence of Yukawa couplings and gauge interactions from worldsheet dynamics. The review further examines flux vacua and magnetized D-branes as a path toward moduli stabilization and SUSY breaking, and it assesses phenomenological implications such as extended gauge sectors, Yukawa textures, FCNCs, proton decay, and cosmology, noting that a fully realistic MSSM vacuum is not yet achieved. Overall, it highlights how the intersecting-brane picture links string theory to low-energy physics, while emphasizing the need for broader backgrounds and flux-based mechanisms to reach a fully predictive, stable vacuum.

Abstract

We provide a pedagogical introduction to a recently studied class of phenomenologically interesting string models, known as Intersecting D-Brane Models. The gauge fields of the Standard-Model are localized on D-branes wrapping certain compact cycles on an underlying geometry, whose intersections can give rise to chiral fermions. We address the basic issues and also provide an overview of the recent activity in this field. This article is intended to serve non-experts with explanations of the fundamental aspects, and also to provide some orientation for both experts and non-experts in this active field of string phenomenology.

Figures (8)

• Figure 1: Intersecting D6-branes
• Figure 2: Oriented intersection
• Figure 3: Intersecting D6-branes on a torus
• Figure 4: Schematic image of an $\Omega\overline\sigma (-1)^{F_L}$ orientifold with O6-planes and intersecting D6-branes. In reality the O6-plane and the $D6$-branes would cover the entire flat Minkowski space.
• Figure 5: Green-Schwarz mechanism