D-brane Deconstructions in IIB Orientifolds

TL;DR

This paper develops techniques to analyze D7-branes in type IIB Calabi-Yau orientifolds, addressing singularities and deriving charge and flux formulae through F-theory and tachyon condensation, with applications to model building.

Contribution

It introduces new methods for handling singular D7-branes, derives consistent charge and flux formulas, and provides explicit recipes for constructing flux vacua in Calabi-Yau orientifolds.

Findings

Corrected charge and flux formulas for singular D7-branes.

Systematic construction of D-brane flux vacua.

Illustration of brane recombination leading to flux creation.

Abstract

With model building applications in mind, we collect and develop basic techniques to analyze the landscape of D7-branes in type IIB compact Calabi-Yau orientifolds, in three different pictures: F-theory, the D7 worldvolume theory and D9-anti-D9 tachyon condensation. A significant complication is that consistent D7-branes in the presence of O7^- planes are generically singular, with singularities locally modeled by the Whitney Umbrella. This invalidates the standard formulae for charges, moduli space and flux lattice dimensions. We infer the correct formulae by comparison to F-theory and derive them independently and more generally from the tachyon picture, and relate these numbers to the closed string massless spectrum of the orientifold compactification in an interesting way. We furthermore give concrete recipes to explicitly and systematically construct nontrivial D-brane worldvolume flux vacua in arbitrary Calabi-Yau orientifolds, illustrate how to read off D-brane flux content, enhanced gauge groups and charged matter spectra from tachyon matrices, and demonstrate how brane recombination in general leads to flux creation, as required by charge conservation and by equivalence of geometric and gauge theory moduli spaces.