Del Pezzo Surfaces and Affine 7-brane Backgrounds
Tamas Hauer, Amer Iqbal
TL;DR
The paper builds a precise bridge between two realizations of four-dimensional ${\cal N}=2$ theories with $E_N$ global symmetry: IIA geometric engineering on shrinking del Pezzo surfaces and IIB D3-brane probes near affine ${\widehat{E}}_N$ 7-brane backgrounds. Using mirror symmetry, it identifies the lattice of string junctions on affine 7-branes with the K-theory lattice of del Pezzo surfaces, and provides an explicit map between vector bundles on del Pezzo surfaces and junctions, including a detailed matching of charges and intersections. A Fourier–Mukai transform on the del Pezzo side is shown to correspond to the ${\rm SL}(2,\mathbb{Z})$ S-duality of the IIB 7-brane background, establishing a deep duality between geometric data and brane dynamics. The results illuminate the role of affine $E_9$ structures in the dual descriptions, relate moduli spaces of bundles to junction genera, and offer a framework for translating D-brane configurations into sheaf-theoretic data via the Fourier–Mukai transform. This work advances the unification of geometric engineering, mirror symmetry, and brane dualities in the study of ${\cal N}=2$ theories with exceptional global symmetry.
Abstract
A map between string junctions in the affine 7-brane backgrounds and vector bundles on del Pezzo surfaces is constructed using mirror symmetry. It is shown that the lattice of string junctions with support on an affine 7-brane configuration is isomorphic to the K-theory group of the corresponding del Pezzo surface. This isomorphism allows us to construct a map between the states of the N=2, D=4 theories with E_N global symmetry realized in two different ways in Type IIB and Type IIA string theory. A subgroup of the SL(2,Z) symmetry of the \hat{E}_9 7-brane background appears as the Fourier-Mukai transform acting on the D-brane configurations realizing vector bundles on elliptically fibered B_9.
