Progress in D-brane model building

TL;DR

This review surveys progress in constructing semi-realistic D-brane vacua in Type II string theories, emphasizing D=4 ${\cal N}=1$ models from intersecting D6-branes and their Type IIB counterparts. It analyzes how D-branes couple to fluxes and Calabi–Yau or non-geometric backgrounds, and how fluxes alter D-brane spectra, moduli stabilization, and SUSY breaking. It highlights explicit toroidal and Gepner-inspired constructions, the emergence of coisotropic D8-branes, and the crucial interplay between open and closed string sectors, including non-perturbative instanton effects. The discussion also covers challenges such as RR-tadpole cancellation, Yukawa textures, and the extent to which fluxes facilitate realistic model-building, outlining a broad, interconnected landscape of techniques linking string theory to particle physics.

Abstract

The state of the art in D-brane model building is briefly reviewed, focusing on recent achievements in the construction of D=4 N = 1 type II string vacua with semi-realistic gauge sectors. Such progress relies on a better understanding of the spectrum of BPS D-branes, the effective field theory obtained from them and the explicit construction of vacua. We first consider D-branes in standard Calabi-Yau compactifications, and then the more involved case of compactifications with fluxes. We discuss how the non-trivial interplay between D-branes and fluxes modifies the previous model-building rules, as well as provides new possibilities to connect string theory to particle physics.

Figures (6)

• Figure 1: Two flat D6-branes intersecting at angles.
• Figure 2: Intersecting brane worlds.
• Figure 3: Worldsheet instantons as generators of a) masses for vector-like pairs and b) Yukawa couplings.
• Figure 4: Models discussed in the text in terms of geometrical and 2D CFT properties.
• Figure 5: Two-step procedure for building $D=4$ models based on D3-branes at singularities. Figure taken from aiqu00.