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Speaker: Thorsten SchimannekTitle: M-theory on nodal Calabi-Yau 3-folds and torsion refined GV-invariantsVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Thorsten Schimannek (Utrecht University) Title: M-theory on nodal Calabi-Yau 3-folds and torsion refined GV-invariants Abstract: The physics of M-theory and Type IIA strings on a projective nodal CY 3-folds is determined by the geometry of a small resolution, even if the latter is not Kähler. We will demonstrate this explicitly in the context of a family of Calabi-Yau double covers of P^3. Using conifold transitions, we prove that the exceptional curves in any small resolution are torsion while M-theory develops a discrete gauge symmetry.This leads to a torsion refinement of the ordinary Gopakumar-Vafa invariants, that is associated to the singular Calabi-Yau and captures the enumerative geometry of the non-Kähler resolutions. We further argue that… |
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Speaker: Maksym FedorchukTitle: CM-minimizers and standard models of Fano fibrations over curvesVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Maksym Fedorchuk (Boston College) Title: CM-minimizers and standard models of Fano fibrations over curves Abstract: A recent achievement in K-stability of Fano varieties is an algebro-geometric construction of a projective moduli space of K-polystable Fanos. The ample line bundle on this moduli space is the CM line bundle of Tian. One of the consequences of the general theory is that given a family of K-stable Fanos over a punctured curve, the polystable filling is the one that minimizes the degree of the CM line bundle after every finite base change. A natural question is to ask what are the CM-minimizers without base change. In answering this question, we arrive at a… |
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Speaker: An HuangTitle: A p-adic Laplacian on the Tate curveVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: An Huang (Brandeis) Pre-talk Speaker: TBA: 10:00-10:30 am Title: A p-adic Laplacian on the Tate curve Abstract: We shall first explain the relation between a family of deformations of genus zero p-adic string worldsheet action and Tate’s thesis. We then propose a genus one p-adic string worldsheet action. The key is the definition of a p-adic Laplacian operator on the Tate curve. We show that the genus one p-adic Green’s function exists, is unique under some obvious constraints, is locally constant off diagonal, and has a reflection symmetry. It can also be numerically computed exactly off the diagonal, thanks to some simplifications due to the p-adic setup. Numerics suggest that at… |
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Speaker: Sheldon KatzTitle: Stacky small resolutions of determinantal octic double solids and noncommutative Gopakumar-Vafa invariantsVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Sheldon Katz, UIUC Title: Stacky small resolutions of determinantal octic double solids and noncommutative Gopakumar-Vafa invariants Abstract: A determinantal octic double solid is the double cover X of P^3 branched along the degree 8 determinant of a symmetric matrix of homogeneous forms on P^3. These X are nodal CY threefolds which do not admit a projective small resolution. B-model techniques can be applied to compute GV invariants up to g \le 32. This raises the question: what is the geometric meaning of these invariants? Evidence suggests that these enumerative invariants are associated with moduli stacks of coherent sheaves of modules over a sheaf B of noncommutative algebras on X constructed by… |
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Speaker: Andrew HarderTitle: Deformations of Landau-Ginzburg models and their fibersVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Andrew Harder, Lehigh University Pre-talk Speaker: TBA: 10:00-10:30 am Title: Deformations of Landau-Ginzburg models and their fibers Abstract: In mirror symmetry, the dual object to a Fano variety is a Landau-Ginzburg model. Broadly, a Landau-Ginzburg model is quasi-projective variety Y with a superpotential function w, but not all such pairs correspond to Fano varieties under mirror symmetry, so a very natural question to ask is: Which Landau-Ginzburg models are mirror to Fano varieties? In this talk, I will discuss a cohomological characterization of mirrors of (semi-)Fano varieties, focusing on the case of threefolds. I’ll discuss how this characterization relates to the deformation and Hodge theory of (Y,w), and in particular, how the… |
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Speaker: David FaveroTitle: Gauged Linear Sigma Models and Cohomological Field TheoriesVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: David Favero, University of Minnesota Title: Gauged Linear Sigma Models and Cohomological Field Theories Abstract: This talk is dedicated to the memory of my friend and collaborator Bumsig Kim and based on joint work with Ciocan-Fontanine-Guere-Kim-Shoemaker. Gauged Linear Sigma Models (GLSMs) serve as a means of interpolating between Kahler geometry and singularity theory. In enumerative geometry, they should specialize to both Gromov-Witten and Fan-Jarvis-Ruan-Witten theory. In joint work with Bumsig Kim (see arXiv:2006.12182), we constructed such enumerative invariants for GLSMs. Furthermore, we proved that these invariants form a Cohomological Field Theory. In this lecture, I will describe GLSMs and Cohomological Field Theories, review the history of their development in enumerative geometry, and discuss… |
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Speaker: Dori BejleriTitle: Moduli of boundary polarized Calabi-Yau pairsVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Pre-talk Speaker: Rosie Shen (Harvard): 10:00-10:30 am Pre-talk Title: Introduction to the singularities of the MMP Speaker: Dori Bejleri (Harvard Math & CMSA) Title: Moduli of boundary polarized Calabi-Yau pairs Abstract: The theories of KSBA stability and K-stability furnish compact moduli spaces of general type pairs and Fano pairs respectively. However, much less is known about the moduli theory of Calabi-Yau pairs. In this talk I will present an approach to constructing a moduli space of Calabi-Yau pairs which should interpolate between KSBA and K-stable moduli via wall-crossing. I will explain how this approach can be used to construct projective moduli spaces of plane curve pairs. This is based on joint work… |
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Speaker: Kai XuTitle: Motivic decomposition of moduli space from brane dynamicsVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Pre-talk Speaker: Kai Xu (CMSA): 10:00-10:30 am Speaker: Kai Xu (CMSA) Title: Motivic decomposition of moduli space from brane dynamics Abstract: Supersymmetric gauge theories encode deep structures in algebraic geometry, and geometric engineering gives a powerful way to understand the underlying structures by string/M theory. In this talk we will see how the dynamics of M5 branes tell us about the motivic and semiorthogonal decompositions of moduli of bundles on curves. |
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Speaker: Damian van de HeisteegTitle: Species Scale across String Moduli SpacesVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Pre-talk Speaker: David Wu (Harvard Physics): 10:00-10:30 am Speaker: Damian van de Heisteeg, CMSA Title: Species Scale across String Moduli Spaces Abstract: String theories feature a wide array of moduli spaces. We propose that the energy cutoff scale of these theories – the so-called species scale – can be determined through higher-curvature corrections. This species scale varies with the moduli; we use it both asymptotically to bound the diameter of the field space, as well as in the interior to determine a “desert point” where it is maximized. |
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Speaker: Oliver SchlottererTitle: Modular graph forms and iterated integrals in string amplitudesVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Oliver Schlotterer (Uppsala University) Title: Modular graph forms and iterated integrals in string amplitudes Abstract: I will discuss string amplitudes as a laboratory for special functions and period integrals that drive fruitful cross-talk with particle physicists and mathematicians. At genus zero, integration over punctures on a disk or sphere worldsheet generates multiple zeta values in the low-energy expansion of open- and closed-string amplitudes. At genus one, closed-string amplitudes introduce infinite families of non-holomorphic modular forms through the integration over torus punctures known as modular graph forms. The latter inspired Francis Brown’s alternative construction of non-holomorphic modular forms in the mathematics literature via iterated integrals, and I will report on recent progress… |
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Speaker: Chung-Ming PanTitle: Kähler-Einstein metrics on families of Fano varietiesVenue: CMSA Room G02Algebraic Geometry in String Theory Seminar Speaker: Chung-Ming Pan, Institut de Mathématiques de Toulouse Title: Kähler-Einstein metrics on families of Fano varieties Abstract: This talk aims to introduce a pluripotential approach to study uniform a priori estimates of Kähler-Einstein (KE) metrics on families of Fano varieties. I will first recall basic tools in the pluripotential theory and the variational approach to complex Monge-Ampère equations. I will then define a notion of convergence of quasi-plurisubharmonic functions in families of normal varieties and extend several classical properties under this context. Last, I will explain how these elements help to obtain a purely analytic proof of the openness of existing singular KE metrics and a uniform $L^\infty$ estimate of KE potentials. This… |
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Speaker: Chao-Ming LinTitle: On the convexity of general inverse $\sigma_k$ equations and some applicationsVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Chao-Ming Lin (University of California, Irvine) Title: On the convexity of general inverse $\sigma_k$ equations and some applications Abstract: In this talk, I will show my recent work on general inverse $\sigma_k$ equations and the deformed Hermitian-Yang-Mills equation (hereinafter the dHYM equation). First, I will show my recent results. This result states that if a level set of a general inverse $\sigma_k$ equation (after translation if needed) is contained in the positive orthant, then this level set is convex. As an application, this result justifies the convexity of the Monge-Ampère equation, the J-equation, the dHYM equation, the special Lagrangian equation, etc. Second, I will introduce some semialgebraic sets and a special… |
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Speaker: Ahsan KhanTitle: 2-Categories and the Massive 3d A-ModelVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Ahsan Khan, IAS Title: 2-Categories and the Massive 3d A-Model Abstract: I will outline the construction of a 2-category associated to a hyperKahler moment map. The construction is based on partial differential equations in one, two, and three dimensions combined with a three-dimensional version of the Gaiotto-Moore-Witten web formalism. |
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Speaker: Nicolo PiazzalungaTitle: The index of M-theoryVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Nicolo Piazzalunga, Rutgers Title: The index of M-theory Abstract: I’ll introduce the higher-rank Donaldson-Thomas theory for toric Calabi-Yau threefolds, within the setting of equivariant K-theory. I’ll present a factorization conjecture motivated by Physics. As a byproduct, I’ll discuss some novel properties of equivariant volumes, as well as their generalizations to the genus-zero Gromov-Witten theory of non-compact toric varieties. |
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Speaker: Daniel PomerleanoTitle: Singularities of the quantum connection on a Fano varietyVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Daniel Pomerleano, UMass Boston Title: Singularities of the quantum connection on a Fano variety Abstract: The small quantum connection on a Fano variety is one of the simplest objects in enumerative geometry. Nevertheless, it is the subject of far-reaching conjectures known as the Dubrovin/Gamma conjectures. Traditionally, these conjectures are made for manifolds with semi-simple quantum cohomology or more generally for Fano manifolds whose quantum connection is of unramified exponential type at q=\infty. I will explain a program, joint with Paul Seidel, to show that this unramified exponential type property holds for all Fano manifolds M carrying a smooth anticanonical divisor D. The basic idea of our argument is to view these structures through… |
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Speaker: Sam Bardwell-EvansTitle: Scattering Diagrams from Holomorphic Discs in Log Calabi-Yau SurfacesVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Sam Bardwell-Evans, Boston University Title: Scattering Diagrams from Holomorphic Discs in Log Calabi-Yau Surfaces Abstract: In this talk, we construct special Lagrangian fibrations for log Calabi-Yau surfaces and scattering diagrams from Lagrangian Floer theory of the fibers. These scattering diagrams recover the algebro-geometric scattering diagrams of Gross-Pandharipande-Siebert and Gross-Hacking-Keel. The argument relies on a holomorphic/tropical disc correspondence to control the behavior of holomorphic discs, allowing us to relate open Gromov-Witten invariants to log Gromov-Witten invariants. This talk is based on joint work with Man-Wai Mandy Cheung, Hansol Hong, and Yu-Shen Lin. |
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Speaker: Mauricio RomoTitle: GLSM, Homological projective duality and nc resolutionsVenue: CMSA Room G10Algebraic Geometry in String Theory Seminar Speaker: Mauricio Romo, Tsinghua University Title: GLSM, Homological projective duality and nc resolutions Abstract: Kuznetsov’s Homological projective duality (HPD) in algebraic geometry is a powerful theorem that allows to extract information about semiorthogonal decompositions of derived categories of certain varieties. I will give a GLSMs perspective based on categories of B-branes. I will focus mostly on the case of Fano (hypersurfaces) manifolds. In general, for such cases the HPD can be interpreted as a non-commutative (nc) resolution of a compact variety. I will give a physical interpretation of this fact and present some conjectures. |
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Speaker: Yan ZhouTitle: Modularity of mirror families of log Calabi–Yau surfacesVenue: virtualAbstract: In “Mirror symmetry for log Calabi–Yau surfaces I,” given a smooth log Calabi–Yau surface pair (Y,D), Gross–Hacking–Keel constructed its mirror family as the spectrum of an explicit algebra whose structure coefficients are determined by the enumerative geometry of (Y,D). As a follow-up of the work of Gross–Hacking–Keel, when (Y,D) is positive, we prove the modularity of the mirror family as the universal family of log Calabi-Yau surface pairs deformation equivalent to (Y,D) with at worst du Val singularities. As a corollary, we show that the ring of regular functions of a smooth affine log Calabi–Yau surface has a canonical basis of theta functions. The key step towards the proof of the main theorem is the application of… |
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Speaker: Ming ZhangTitle: Equivariant Verlinde algebra and quantum K-theory of the moduli space of vorticesVenue: VirtualAbstract: In studying complex Chern-Simons theory on a Seifert manifold, Gukov-Pei proposed an equivariant Verlinde formula, a one-parameter deformation of the celebrated Verlinde formula. It computes, among many things, the graded dimension of the space of holomorphic sections of (powers of) a natural determinant line bundle over the Hitchin moduli space. Gukov-Pei conjectured that the equivariant Verlinde numbers are equal to the equivariant quantum K-invariants of a non-compact (Kahler) quotient space studied by Hanany-Tong. In this talk, I will explain the setup of this conjecture and its proof via wall-crossing of moduli spaces of (parabolic) Bradlow-Higgs triples. It is based on work in progress with Wei Gu and Du Pei. |
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Speaker: Aron HeleodoroTitle: Applications of Higher Determinant MapVenue: VirtualAbstract: In this talk I will explain the construction of a determinant map for Tate objects and two applications: (i) to construct central extensions of iterated loop groups and (ii) to produce a determinant theory on certain ind-schemes. For that I will introduce some aspects of the theory of Tate objects in a couple of contexts. |