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Etienne Mann

Publications and source records attributed to Etienne Mann.

16 recordsLinked to original sources
arXiv2025

Irreducible components of moduli spaces of maps to smooth projective toric varieties in genus 0

We give a combinatorial description of the irreducible components of the moduli space $\overline{\mathcal{M}}_{0,n}(X,β)$ for a smooth projective toric variety $X$. The result is based on the study of the irreducible components of an abelian cone over a smooth Noetherian Artin stack. We give concrete applications of the result including $\overline{\mathcal{M}}_{0,0}(Bl_{pt} \mathbb{P}^2,2\ell)$, where we also describe the main component. This is the first example where the smoothable locus of $\overline{\mathcal{M}}_{g,n}(X,β)$ is described for $X$ not a projective space.

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arXiv2023

Higher genus reduced Gromov--Witten invariants via desingularizations of sheaves

Given $\mathfrak{F}$ a coherent sheaf on a Noetherian integral algebraic stack $\mathfrak{P}$, we give two constructions of stacks $\widetilde{\mathfrak{P}}$, equipped with birational morphisms $p:\widetilde{\mathfrak{P}}\to \mathfrak{P}$ such that $p^*\mathfrak{F}$ is simpler: in the Rossi construction, the torsion free part of $p^*\mathfrak{F}$ is locally free; in the Hu--Li diagonalization construction, $p^*\mathfrak{F}$ is a union of locally free sheaves. We use these constructions to define reduced Gromov--Witten invariants of a large class of GIT quotients in all genera.

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arXiv2022

Derived moduli of sections and push-forwards

We introduce a derived enhancement of the moduli space of sections defined by Chang-Li, and we compute its tangent complex. Special cases of this moduli space include stable maps and stable quasi-maps. As an application, we prove that G-theoretic stable map and quasi-map invariants of projective spaces are equal.

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arXiv2018

Gromov-Witten theory with derived algebraic geometry

In this survey we add two new results that are not in our paper [MR15]. Using the idea of brane actions discovered by Toen, we construct a lax associative action of the operad of stable curves of genus zero on a smooth variety X seen as an object in correspondences in derived stacks. This action encodes the Gromov-Witten theory of X in purely geometrical terms.

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arXiv2017

Brane actions, Categorification of Gromov-Witten theory and Quantum K-theory

Let X be a smooth projective variety. Using the idea of brane actions discovered by Toën, we construct a lax associative action of the operad of stable curves of genus zero on the variety X seen as an object in correspondences in derived stacks. This action encodes the Gromov-Witten theory of X in purely geometrical terms and induces an action on the derived category Qcoh(X) which allows us to recover the Quantum K-theory of Givental-Lee.

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arXiv2017

Quantum D-modules for toric nef complete intersections

On a smooth projective variety with k ample line bundles, we denote by Z the complete intersection subvariety defined by generic sections. We define the twisted quantum D-module which is a vector bundle with a flat connection, a flat pairing and a natural integrable structure. An appropriate quotient of it is isomorphic to the ambient part of the quantum D-module of Z. When the variety is toric, these quantum D-modules are cyclic. The twisted quantum D-module can be presented via mirror symmetry by the GKZ system associated to the total space of the dual of the direct sum of these line bundles. A question is to know what is the system of equations that define the ambiant part of the quantum D-module of Z. We construct this system as a quotient ideal of the GKZ system. We also state and prove the non-equivariant twisted Gromov-Witten axioms in the appendix.

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arXiv2016

Logarithmic degenerations of Landau-Ginzburg models for toric orbifolds and global tt^* geometry

We discuss the behavior of Landau-Ginzburg models for toric orbifolds near the large volume limit. This enables us to express mirror symmetry as an isomorphism of Frobenius manifolds which aquire logarithmic poles along a boundary divisor. If the toric orbifold admits a crepant resolution we construct a global moduli space on the B-side and show that the associated tt^*-geometry exists globally.

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arXiv2015

Quantum Serre theorem as a duality between quantum D-modules

We give an interpretation of quantum Serre of Coates and Givental as a duality of twisted quantum D-modules. This interpretation admits a non-equivariant limit, and we obtain a precise relationship among (1) the quantum D-module of X twisted by a convex vector bundle E and the Euler class, (2) the quantum D-module of the total space of the dual bundle E^\vee over X, and (3) the quantum D-module of a submanifold Z\subset X cut out by a regular section of E. When E is the anticanonical line bundle K_X^{-1}, we identify these twisted quantum D-modules with second structure connections with different parameters, which arise as Fourier-Laplace transforms of the quantum D-module of X. In this case, we show that the duality pairing is identified with Dubrovin's second metric (intersection form).

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arXiv2012

The small quantum cohomology of a weighted projective space, a mirror D-module and their classical limits

We first describe a canonical mirror partner (B-model) of the small quantum orbifold cohomology of weighted projective spaces (A-model) in the framework of differential equations: we attach to the A-model (resp. B-model) a D-module on the torus and we show that these two D-modules are isomorphic. This makes the A and B-models mirror partners and yields, in this situation, an explicit and finer version of a recent result of Iritani. Then we study, using the theory of the Kashiwara-Malgrange filtration, their degenerations at the origin and we apply our results to the construction of (classical, limit, logarithmic) Frobenius manifolds.

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arXiv2009

Smooth toric DM stacks

We give a new definition of smooth toric DM stacks in the same spirit of toric varieties. We show that our definition is equivalent to the one of Borisov, Chen and Smith in terms of stacky fans. In particular, we give a geometric interpretation of the combinatorial data contained in a stacky fan. We also give a bottom up classification in terms of simplicial toric varieties and fiber products of root stacks.

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arXiv2007

The cohomological crepant resolution conjecture for P(1,3,4,4)

We prove the cohomological crepant resolution conjecture of Ruan for the weighted projective space P(1,3,4,4). To compute the quantum corrected cohomology ring we combine the results of Coates-Corti-Iritani-Tseng on P(1,1,1,3) and our previous results.

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arXiv2007

Crepant resolutions of weighted projective spaces and quantum deformations

We compare the Chen-Ruan cohomology ring of the weighted projective spaces $\IP(1,3,4,4)$ and $\IP(1,...,1,n)$ with the cohomology ring of their crepant resolutions. In both cases, we prove that the Chen-Ruan cohomology ring is isomorphic to the quantum corrected cohomology ring of the crepant resolution after suitable evaluation of the quantum parameters. For this, we prove a formula for the Gromov-Witten invariants of the resolution of a transversal ${\rm A}_3$ singularity.

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arXiv2006

Orbifold quantum cohomology of weighted projective spaces

This article is a revised, short and english version of my PhD thesis. First, we show a mirror theorem : the Frobenius manifold associated to the orbifold quantum cohomology of weighted projective space is isomorphic to the one attached to a specific Laurent polynomial. Secondly, we show a reconstruction theorem, that is, we can reconstruct in an algorithmic way the full genus 0 Gromov-Witten potential from the 3-point invariants.

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arXiv2005

Cohomologie quantique orbifolde des espaces projectifs a poids

In 2001, S. Barannikov showed that the Frobenius manifold coming from the quantum cohomology of the complex projective space is isomorphic to the Frobenius manifold attached to some Laurent polynomial. The purpose of this thesis is to generalize this result. More precisely, we show, up to a conjecture on the value of some orbifold Gromov-Witten invariants, that the Frobenius structure obtained on the orbifold quantum cohomology of the weighted projective spaces is isomorphic to the one attached to some Laurent polynomial.

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