Toric Duality as Seiberg Duality and Brane Diamonds

In this review, novel non-standard techniques for the computation of cohomology classes on toric varieties are summarized. After an introduction of the basic definitions and properties of toric geometry, we discuss a specific computational algorithm for the determination of the dimension of line-bundle valued cohomology groups on toric varieties. Applications to the computation of chiral massless matter spectra in string compactifications are discussed and, using the software...

We develop a method to analyze systematically the configuration space of a D-brane localized at the orbifold singular point of a Calabi--Yau $d$-fold of the form ${\Bbb C}^d/\Gamma$ using the theory of toric quotients. This approach elucidates the structure of the K\"ahler moduli space associated with the problem. As an application, we compute the toric data of the $\Gamma$-Hilbert scheme.

I review the proposal of Berenstein-Douglas for a completely general definition of Seiberg duality. To give evidence for their conjecture I present the first example of a physical dual pair and explicitly check that it satisfies the requirements. Then I explicitly show that a pair of toric dual quivers is also dual according to their proposal. All these computations go beyond tilting modules, and really work in the derived category. I introduce all necessary mathematics where...

This dissertation presents a study of dualities and generalized global symmetries in quantum field theories (QFTs) from the string theory perspective. Chapter 2 is based on the work arXiv:2110.03696 with Sebasti\'{a}n Franco, Alessandro Minino and \'{A}ngel M. Uranga . It introduces a new class of string theory backgrounds, Spin(7) orientifolds, allowing for the engineering of 2$d$ $\mathcal{N}=(0,1)$ gauge theories on D1-branes and illustrating the perspective on 2$d$ $\math...

We present the complete classification of smooth toric Fano threefolds, known to the algebraic geometry literature, and perform some preliminary analyses in the context of brane-tilings and Chern-Simons theory on M2-branes probing Calabi-Yau fourfold singularities. We emphasise that these 18 spaces should be as intensely studied as their well-known counter-parts: the del Pezzo surfaces.

We investigate field theories on the worldvolume of a D3-brane transverse to partial resolutions of a $\Z_3\times\Z_3$ Calabi-Yau threefold quotient singularity. We deduce the field content and lagrangian of such theories and present a systematic method for mapping the moment map levels characterizing the partial resolutions of the singularity to the Fayet-Iliopoulos parameters of the D-brane worldvolume theory. As opposed to the simpler cases studied before, we find a comple...

We propose a way to examine N=1 and N=2 string dualities on Calabi-Yau three-folds or extensions. Our way is to find out or to construct two types of toric representations of a Calabi-Yau three-fold, which contain phases topologically equivalent or phases connected by flops. We discuss how to find relations among Calabi-Yau three-folds realized in different toric representations. We examine several examples of Calabi-Yau three-folds which have the Hodge numbers, $(h^{1,1},h^{...

We study D-brane instantons in systems of D3-branes at toric CY 3-fold singularities. The instanton effect can be described as a backreaction modifying the geometry of the mirror configuration, in which the breaking of $U(1)$ symmetries by the instanton translates into the recombination of gauge D-branes, which also directly generates the instanton-induced charged field theory operator. In this paper we describe the D-brane instanton backreaction in terms of a combinatorial o...

We discuss how N=1 dualities in four dimensions are geometrically realized by wrapping D-branes about 3-cycles of Calabi-Yau threefolds. In this setup the N=1 dualities for SU, SO and USp gauge groups with fundamental fields get mapped to statements about the monodromy and relations among 3-cycles of Calabi-Yau threefolds. The connection between the theory and its dual requires passing through configurations which are T-dual to the well-known phenomenon of decay of BPS states...

We carry out a detailed exploration of the deformations of rank-two five-dimensional superconformal field theories (SCFTs) $\mathcal{T}_{\mathbf{X}}$, which are geometrically engineered by M-theory on the space transverse to isolated toric Calabi-Yau (CY) threefold singularities $\mathbf{X}$. Deformations of 5d $\mathcal{N}=1$ SCFTs can lead to "gauge-theory phases," but also to "non-gauge-theoretic phases," which have no known Lagrangian interpretation. In previous work, a t...