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Tsung-Ju Lee

Publications and source records attributed to Tsung-Ju Lee.

17 recordsLinked to original sources
arXiv2026

Non-commutative resolutions as mirrors of singular Calabi--Yau varieties

It has been conjectured that the hemisphere partition function arXiv:1308.2217, arXiv:1308.2438 in a gauged linear sigma model (GLSM) computes the central charge arXiv:math/0212237 of an object in the bounded derived category of coherent sheaves for Calabi--Yau (CY) manifolds. There is also evidence in arXiv:alg-geom/ 9511001, arXiv:hep-th/0007071. On the other hand, non-commutative resolutions of singular CY varieties have been studied in the context of abelian GLSMs arXiv:0709.3855. In this paper, we study an analogous construction of abelian GLSMs for non-commutative resolutions and propose they can be used to study a class of recently discovered mirror pairs of singular CY varieties. Our main result shows that the hemisphere partition functions (a.k.a. $A$-periods) in the new GLSM are in fact period integrals (a.k.a. $B$-periods) of the singular CY varieties. We conjecture that the two are completely equivalent: $B$-periods are the same as $A$-periods. We give some examples to support this conjecture and formulate some expected homological mirror symmetry (HMS) relation between the GLSM theory and the CY. As shown in arXiv:2003.07148, the $B$-periods in this case are precisely given by a certain fractional version of the $B$-series of arXiv:alg-geom/9511001. Since a hemisphere partition function is defined as a contour integral in a cone in the complexified secondary fan (or FI-theta parameter space) arXiv:1308.2438, it can be reduced to a sum of residues (by theorems of Passare--Tsikh--Zhdanov and Tsikh--Zhdanov). Our conjecture shows that this residue sum may now be amenable to computations in terms of the $B$-series.

hep-th↗
arXiv2025

Mirror symmetry for singular double cover Calabi--Yau varieties: quantum test

We continue our study on the pairs of singular Calabi--Yau varieties arising from double covers over semi-Fano toric manifolds. In this paper, we first investigate singular CY double covers of \(\mathbb{P}^{3}\) branched along (1) a union of eight hyperplanes in general position, and (2) a union of four hyperplanes and a quartic in generation. Our previous construction produces hypothetical singular mirror partners. We prove that they are mirror pairs in the sense that the \(B\)-model of one (variation of Hodge structure) is equivalent to the \(A\)-model of another (the untwisted part of the genus zero orbifold Gromov--Witten invariants). The technique can be generalized and applied to the case when the nef-partition is trivial. As a byproduct, we also verify Morrison's conjecture in certain circumstances.

math.AG↗
arXiv2025

Non-commutative resolutions and pre-quotients of Calabi-Yau double covers

Following an earlier proposal arXiv:2307.02038 to apply the GLSM formalism to understand the so-called non-commutative resolution, this paper takes one important step further to extend this formalism to a much larger class of non-commutative resolutions. The proposal was initially motivated by the discovery of a new class of mirror pairs singular Calabi-Yau varieties arXiv:2003.07148, given by certain branched double covers over toric varieties of MPCP type. The overarching problem was to understand these mirror pairs from the viewpoint of homological mirror symmetry arXiv:alg-geom/9411018. In the present paper, we propose two main results along this line. First, one new insight is that the `gauge-fixing' condition on the branching locus of the double cover used in arXiv:2003.07148 can be relaxed in an interesting way. This turns out to produce GLSMs that describe a much larger class of non-commutative resolutions, leading to $A$-periods for a larger class of non-commutative resolutions, as well as the GKZ systems for their $A$-periods. Second, we show that the $A$-periods can also be realized as $A$-periods of a certain smooth CICY family in a toric variety of MPCP type, such that a suitable finite quotient of this family recovers the double cover CY we have started with. We call this CICY family the `pre-quotient' of the double cover CY. This realization strongly suggests that pre-quotient may provide an important approach for understanding homological mirror symmetry for singular double cover CY varieties and non-commutative resolutions.

hep-th↗
arXiv2024

Finite distance problem on the moduli of non-Kähler Calabi--Yau $\partial\bar{\partial}$-threefolds

In this article, we study the finite distance problem with respect to the period-map metric on the moduli of non-Kähler Calabi--Yau $\partial\bar{\partial}$-threefolds via Hodge theory. We extended C.-L. Wang's finite distance criterion for one-parameter degenerations to the present setting. As a byproduct, we also obtained a sufficient condition for a non-Kähler Calabi--Yau to support the $\partial\bar{\partial}$-lemma which generalizes the results by Friedman and Li. We also proved that the non-Kähler Calabi--Yau threefolds constructed by Hashimoto and Sano support the $\partial\bar{\partial}$-lemma.

math.AG↗
arXiv2024

SYZ mirror symmetry for del Pezzo surfaces and affine structures

We prove that the Landau--Ginzburg superpotential of del Pezzo surfaces can be realized as a limit of their hyperKähler rotation toward the large complex structure limit point. As a corollary, we compute the limit of the complex affine structure of the special Lagrangian fibrations constructed by Collins--Jacob--Lin in $\mathbf{P}^1\times \mathbf{P}^1$ arXiv:1904.08363 and compare it with the integral affine structures used in the work of Carl--Pumperla--Siebert arXiv:2205.07753. We also construct the Floer-theoretical Landau--Ginzburg mirrors of smoothing of $A_n$-singularities and monotone del Pezzo surfaces, by using the gluing method of Cho--Hong--Lau arXiv:1810.02045 and Hong--Kim--Lau arXiv:1805.11738. They agree with the result of hyperKähler rotation.

math.AG↗
arXiv2023

On a conjecture of Huang--Lian--Yau--Yu

We verify a formula on the solution rank of the tautological system arising from ample complete intersections in a projective homogeneous space of a semisimple group conjectured by Huang--Lian--Yau--Yu arXiv:1801.01194. As an application, we prove the existence of the rank one point for such a system, where mirror symmetry is expected.

math.AG↗
arXiv2023

Twisted GKZ hypergeometric functions and relative cohomology

We investigate the GKZ $A$-hypergeometric $\mathscr{D}$-modules, introduced by Gel'fand, Kapranov, and Zelevinskii, arising from cyclic covers of toric varieties and find its Riemann--Hilbert partner. This extends our earlier results in arXiv:1902.01536.

math.AG↗
arXiv2022

Period domains for gravitational instantons

Based on the uniformization theorems of gravitation instantons by Chen--Chen arXiv:1505.01790, Chen--Viaclovsky arXiv:2110.06498, Collins--Jacob--Lin arXiv:2111.09260, and Hein--Sun--Viaclovsky--Zhang arXiv:2111.09287, we prove that the period maps for the ALH*, ALG, and ALG* gravitational instantons are surjective.

math.DG↗
arXiv2022

Mirror duality between Calabi-Yau fractional complete intersections

This is an expanded version of the author's talk at the third annual meeting of International Consortium of Chinese Mathematicians held at USTC in December 2020. In this expository article, we give a survey on joint works with Hosono, Lian, and Yau in arXiv:2003.07148 and arXiv:2008.04039. We also carry out some explicit examples to illustrate our results in enumerative geometry which will appear in our forthcoming papers.

math.AG↗
arXiv2022

A note on periods of Calabi--Yau fractional complete intersections

We prove that the GKZ $\mathscr{D}$-module $\mathcal{M}_{A}^β$ arising from Calabi--Yau fractional complete intersections in toric varieties is complete, i.e., all the solutions to $\mathcal{M}_{A}^β$ are period integrals. This particularly implies that $\mathcal{M}_{A}^β$ is equivalent to the Picard--Fuchs system. As an application, we give explicit formulae of the period integrals of Calabi--Yau threefolds coming from double covers of $\mathbf{P}^{3}$ branch over eight hyperplanes in general position.

math.AG↗
arXiv2022

On Calabi--Yau fractional complete intersections

In this article, we study mirror symmetry for pairs of singular Calabi--Yau manifolds which are double covers of toric manifolds. Their period integrals can be seen as certain `fractional' analogues of those of ordinary complete intersections. This new structure can then be used to solve their Riemann--Hilbert problems. The latter can then be used to answer definitively questions about mirror symmetry for this class of Calabi--Yau manifolds.

math.AG↗
arXiv2020

Mirror symmetry for double cover Calabi--Yau varieties

The presented paper is a continuation of the series of papers arXiv:1810.00606 and arXiv:1903.09373. In this paper, utilizing Batyrev and Borisov's duality construction on nef-partitions, we generalize the recipe in arXiv:1810.00606 and arXiv:1903.09373 to construct a pair of singular double cover Calabi--Yau varieties $(Y,Y^{\vee})$ over toric manifolds and compute their topological Euler characteristics and Hodge numbers. In the $3$-dimensional cases, we show that $(Y,Y^{\vee})$ forms a topological mirror pair, i.e., $h^{p,q}(Y)=h^{3-p,q}(Y^{\vee})$ for all $p,q$.

math.AG↗
arXiv2020

$A$-hypergeometric systems and relative cohomology

We investigate the space of solutions to certain $A$-hypergeometric $\mathscr{D}$-modules, which were defined and studied by Gelfand, Kapranov, and Zelevinsky. We show that the solution space can be identified with certain relative cohomology group of the toric variety determined by $A$, which generalizes the results of Huang, Lian, Yau, and Zhu. As a corollary, we also prove the existence of rank one points for Calabi--Yau complete intersections in toric varieties.

math.AG↗
arXiv2020

On the Complex Affine Structures of SYZ Fibration of Del Pezzo Surfaces

Given any smooth cubic curve $E\subseteq \mathbb{P}^2$, we show that the complex affine structure of the special Lagrangian fibration of $\mathbb{P}^2\setminus E$ constructed by Collins--Jacob--Lin arXiv:1904.08363 coincides with the affine structure used in Carl--Pomperla--Siebert for constructing mirror. Moreover, we use the Floer-theoretical gluing method to construct a mirror using immersed Lagrangians, which is shown to agree with the mirror constructed by Carl--Pomperla--Siebert.

math.DG↗
arXiv2016

A Hodge theoretic criterion for finite Weil--Petersson degenerations over a higher dimensional base

We give a Hodge-theoretic criterion for a Calabi--Yau variety to have finite Weil--Petersson distance on higher dimensional bases up to a set of codimension $\geq 2$. The main tool is variation of Hodge structures and variation of mixed Hodge structures. We also give a description on the codimension 2 locus for the moduli space of Calabi--Yau threefolds. We prove that the points lying on exactly one finite and one infinite divisor have infinite Weil--Petersson distance along angular slices. Finally, by giving a classification of the dominant term of the candidates of the Weil--Petersson potential, we prove that the points on the intersection of exact two infinite divisors have infinite distance measured by the metric induced from the dominant terms of the candidates of the Weil--Petersson potential.

math.AG↗
arXiv2016

Tautological systems under the conifold transition on $G(2, 4)$

Via a natural degeneration of Grassmannian manifolds $G(k,n)$ to Gorenstein toric Fano varieties $P(k,n)$ with conifold singularities, we suggest an approach to study the relation between the tautological system on $G(k,n)$ and the extended GKZ system on the small resolution $\hat{P}(k,n)$ of $P(k,n)$. We carry out the simplest case $(k,n)=(2,4)$ to ensure its validity and show that the extended GKZ system can be regarded as a tautological system on $\hat{P}(2,4)$.

math.AG↗