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Qile Chen

Publications and source records attributed to Qile Chen.

At least 19 recordsLinked to original sources
arXiv2026

Manin's conjecture for semi-integral curves and $\mathbb A^1$-connectedness

We explore log Manin's conjecture for integral points and its connections to $\mathbb A^1$-connectedness. We prove log Manin's conjecture for Campana rational curves and for $\mathbb A^1$-curves on split toric varieties. Our arguments combine the Cox ring description of the moduli space of rational curves with Batyrev's heuristic-type counting arguments. As our proofs are geometric in nature, they give a geometric explanation of the mysterious leading constant for Campana points proposed by Chow--Loughran--Takloo-Bighash--Tanimoto.

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arXiv2024

Campana rational connectedness and weak approximation

Campana introduced a notion of Campana rational connectedness for Campana orbifolds. Given a Campana fibration over a complex curve, we prove that a version of weak approximation for Campana sections holds at places of good reduction when the general fiber satisfies a slightly stronger version of Campana rational connectedness. Campana also conjectured that any Fano orbifold is Campana rationally connected; we verify a stronger statement for toric Campana orbifolds. A key tool in our study is log geometry and moduli stacks of stable log maps.

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arXiv2024

Gorenstein contractions of multiscale differentials

Multiscale differentials arise as limits of holomorphic differentials with prescribed zero orders on nodal curves. In this paper, we address the conjecture concerning Gorenstein contractions of multiscale differentials, originally proposed by Ranganathan and Wise and further developed by Battistella and Bozlee. Specifically, in the case of a one-parameter degeneration, we show that multiscale differentials can be contracted to Gorenstein singularities, level by level, from the top down. At each level, these differentials descend to generators of the dualizing bundle at the resulting singularities. Moreover, the global residue condition, which governs the smoothability of multiscale differentials, appears as a special case of the residue condition for descent differentials.

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arXiv2023

Towards Logarithmic GLSM: The r-spin case

In this article, we establish the logarithmic foundation for compactifying the moduli stacks of the gauged linear sigma model using stable log maps of Abramovich-Chen-Gross-Siebert. We then illustrate our method via the key example of Witten's $r$-spin class to construct a proper moduli stack with a reduced perfect obstruction theory whose virtual cycle recovers the $r$-spin virtual cycle of Chang-Li-Li. Indeed, our construction of the reduced virtual cycle is built upon the work of Chang-Li-Li by appropriately extending and modifying the Kiem-Li cosection along certain logarithmic boundary. In the subsequent article, we push the technique to a general situation. One motivation of our construction is to fit the gauged linear sigma model in the broader setting of Gromov-Witten theory so that powerful tools such as virtual localization can be applied. A project along this line is currently in progress leading to applications including computing loci of holomorphic differentials, and calculating higher genus Gromov-Witten invariants of quintic threefolds.

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arXiv2023

Punctured logarithmic R-maps

In this paper, we develop the theory of punctured R-maps as a crucial component of logarithmic gauged linear sigma models (log GLSM). A punctured R-map is a punctured map in the sense of ACGS, further twisted by the sheaf of differentials on the domain curve. They admit two different but closely related perfect obstruction theories - a canonical one and a reduced one. While the canonical theory leads to generalized double ramification cycles with targets and spin structures, without expansions, the reduced theory describes boundary contributions in log GLSM. Major results of this paper include a sequence of axioms in both canonical and reduced theories: 1. A product formula computing disconnected invariants in terms of connected ones 2. Fundamental class axioms, string and divisor equations As an important application, these formulas lead to a class of invariants in the reduced theory, called effective invariants. They are at the heart of recent advances in GW theory, and will be shown to give rise to explicit correction terms to the quantum Lefschetz principle in higher genus GW theory for arbitrary smooth complete intersections in a forthcoming paper. For quintic 3-folds, we show that all effective invariants are determined by $[(2g-2)/5] + 1$ many basic effective invariants, using the formulas in (1) and (2). This matches the number of free parameters of the famous BCOV B-model theory in physics. Similar results apply to other complete intersections. This, together with the joint works of the last two authors and S. Guo on the genus two mirror theorem and the higher genus mirror conjectures for quintic 3-folds, shows that log GLSM is an effective tool for proving BCOV-type conjectures in higher genus GW theory. Further applications of punctured R-maps include an LG/CY correspondence for effective invariants and a relation to the locus of holomorphic differentials.

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arXiv2021

Plane $\mathbb{A}^1$-curves on the complement of strange rational curves

A plane curve is called strange if its tangent line at any smooth point passes through a fixed point, called the strange point. In this paper, we study $\mathbb{A}^1$-curves on the complement of a rational strange curve of degree $p$ in characteristic $p$. We prove the connectedness of the moduli spaces of $\mathbb{A}^1$-curves with given degree, classify their irreducible components, and exhibit the inseparable $\mathbb{A}^1$-connectedness via the $\mathbb{A}^1$-curves parameterized by each irreducible component. The key to these results is the strangeness of all $\mathbb{A}^1$-curves. As an application, in every characteristic we construct explicit covering families of $\mathbb{A}^1$-curves, whose total spaces are smooth along large numbers of cusps on each general fiber.

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arXiv2021

Virtual cycles of stable (quasi)-maps with fields

We generalize the results of Chang-Li, Kim-Oh and Chang-Li on the moduli of $p$-fields to the setting of (quasi-)maps to complete intersections in arbitrary smooth Deligne-Mumford stacks with projective coarse moduli. In particular, we show that the virtual cycle of stable (quasi-)maps to a complete intersection can be recovered by the cosection localized virtual cycle of the moduli of $p$-fields of the ambient space.

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arXiv2021

The logarithmic gauged linear sigma model

We introduce the notion of log R-maps, and develop a proper moduli stack of stable log R-maps in the case of a hybrid gauged linear sigma model. Two virtual cycles (canonical and reduced) are constructed for these moduli stacks. The main results are two comparison theorems relating the reduced virtual cycle to the cosection localized virtual cycle, as well as the reduced virtual cycle to the canonical virtual cycle. This sets the foundation of a new technique for computing higher genus Gromov-Witten invariants of complete intersections.

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arXiv2021

Boundedness of the space of stable logarithmic maps

We prove that the moduli space of stable logarithmic maps with fixed numerical invariants, from logarithmic curves to a fixed projective target logarithmic scheme with fine and saturated logarithmic structure, is a proper algebraic stack. This was previously known only with further restrictions on the logarithmic structure of the target.

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arXiv2020

Punctured logarithmic maps

We introduce a variant of stable logarithmic maps, which we call punctured logarithmic maps. They allow an extension of logarithmic Gromov-Witten theory in which marked points have a negative order of tangency with boundary divisors. As a main application we develop a gluing formalism which reconstructs stable logarithmic maps and their virtual cycles without expansions of the target, with tropical geometry providing the underlying combinatorics. Punctured Gromov-Witten invariants also play a pivotal role in the intrinsic construction of mirror partners by the last two authors in arXiv:1909.07649, conjecturally relating to symplectic cohomology, and in the logarithmic gauged linear sigma model in upcoming work of the second author with Felix Janda and Yongbin Ruan.

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arXiv2020

Decomposition of degenerate Gromov-Witten invariants

We prove a decomposition formula of logarithmic Gromov-Witten invariants in a degeneration setting. A one-parameter log smooth family X->B with singular fibre over b_0 \in B yields a family M(X/B,β) -> B of moduli stacks of stable logarithmic maps. We give a virtual decomposition of the fibre of this family over b_0 in terms of rigid tropical curves. This generalizes one aspect of known results in the case that the fibre X_{b_0} is a normal crossings union of two divisors. We exhibit our formulas in explicit examples.

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arXiv2017

$\mathbb{A}^1$-curves on log smooth varieties

In this paper, we study $\mathbb{A}^1$-connected varieties from log geometry point of view, and prove a criterion for $\mathbb{A}^1$-connectedness. As applications, we provide many interesting examples of $\mathbb{A}^1$-connected varieties in the case of complements of ample divisors, and the case of homogeneous spaces. We also obtain a logarithmic version of Hartshorne's conjecture characterizing projective spaces and affine spaces.

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arXiv2016

Principal boundary of moduli spaces of abelian and quadratic differentials

The seminal work of Eskin-Masur-Zorich described the principal boundary of moduli spaces of abelian differentials that parameterizes flat surfaces with a prescribed generic configuration of short parallel saddle connections. In this paper we describe the principal boundary for each configuration in terms of twisted differentials over Deligne-Mumford pointed stable curves. We also describe similarly the principal boundary of moduli spaces of quadratic differentials originally studied by Masur-Zorich. Our main technique is the flat geometric degeneration and smoothing developed by Bainbridge-Chen-Gendron-Grushevsky-Möller.

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arXiv2016

Spin and hyperelliptic structures of log twisted differentials

Using stable log maps, we introduce log twisted differentials extending the notion of abelian differentials to the Deligne-Mumford boundary of stable curves. The moduli stack of log twisted differentials provides a compactification of the strata of abelian differentials. The open strata can have up to three connected components, due to spin and hyperelliptic structures. We prove that the spin parity can be distinguished on the boundary of the log compactification. Moreover, combining the techniques of log geometry and admissible covers, we introduce log twisted hyperelliptic differentials, and prove that their moduli stack provides a toroidal compactification of the hyperelliptic loci in the open strata.

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arXiv2015

Strong approximation over function fields

By studying $\mathbb{A}^1$-curves on varieties, we propose a geometric approach to strong approximation problem over function fields of complex curves. We prove that strong approximation holds for smooth, low degree affine complete intersections with the boundary smooth at infinity.

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arXiv2015

$\mathbb{A}^1$-connected varieties over non-closed fields

In this paper, we proved two results regarding the arithmetics of separably $\mathbb{A}^1$-connected varieties of rank one. First we proved over a large field, there is an $\mathbb{A}^1$-curve through any rational point of the boundary, if the boundary divisor is smooth and separably rationally connected. Secondly, we generalize a theorem of Hassett-Tschinkel for the Zariski density of integral points over function fields of curves.

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arXiv2015

Very free curves on Fano Complete Intersections

In this paper, we show that general Fano complete intersections over an algebraically closed field of arbitrary characteristics are separably rationally connected. Our proof also implies that general log Fano complete intersections with smooth tame boundary divisors admit very free $A^1$-curves.

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