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# Documents  14F05 | enregistrements trouvés : 13

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## Post-edited  The Verlinde formula for Higgs bundles Andersen, Jorgen Ellegaard (Auteur de la Conférence) | CIRM (Editeur )

In this talk we will present a Verlinde formula for the quantization of the Higgs bundle moduli spaces and stacks for any simple and simply-connected group. We further present a Verlinde formula for the quantization of parabolic Higgs bundle moduli spaces and stacks. We will explain how all these dimensions fit into a one parameter family of 2D TQFT’s, encoded in a one parameter family of Frobenius algebras, which we will construct.

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## Post-edited  Wall-crossing for Donaldson-Thomas invariants Bridgeland, Tom (Auteur de la Conférence) | CIRM (Editeur )

There is a very general story, due to Joyce and Kontsevich-Soibelman, which associates to a CY3 (three-dimensional Calabi-Yau) triangulated category equipped with a stability condition some rational numbers called Donaldson-Thomas (DT) invariants. The point I want to emphasise is that the wall-crossing formula, which describes how these numbers change as the stability condition is varied, takes the form of an iso-Stokes condition for a family of connections on the punctured disc, where the structure group is the infinite-dimensional group of symplectic automorphisms of an algebraic torus. I will not assume any knowledge of stability conditions, DT invariants etc.
There is a very general story, due to Joyce and Kontsevich-Soibelman, which associates to a CY3 (three-dimensional Calabi-Yau) triangulated category equipped with a stability condition some rational numbers called Donaldson-Thomas (DT) invariants. The point I want to emphasise is that the wall-crossing formula, which describes how these numbers change as the stability condition is varied, takes the form of an iso-Stokes condition for a family of ...

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## Multi angle  ​Absolute sets and the Decomposition Theorem Budur, Nero (Auteur de la Conférence) | CIRM (Editeur )

We give a new, more conceptual proof of the Decomposition Theorem for semisimple perverse sheaves of rank-one origin, assuming it for those of constant-sheaf origin, that is, assuming the geometric case proven by Beilinson-Bernstein-Deligne-Gabber. Joint work with Botong Wang.

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## Multi angle  Quantum character varieties at roots of unity Safronov, Pavel (Auteur de la Conférence) | CIRM (Editeur )

Character varieties of closed surfaces have a natural Poisson structure whose quantization may be constructed in terms of the corresponding quantum group. When the quantum parameter is a root of unity, this quantization carries a central subalgebra isomorphic to the algebra of functions on the classical character variety. In this talk I will describe a procedure which allows one to obtain Azumaya algebras via quantum Hamiltonian reduction. As an application, I will show that quantizations of character varieties at roots of unity are Azumaya over the corresponding classical character varieties.
This is a report on joint work with Iordan Ganev and David Jordan.
Character varieties of closed surfaces have a natural Poisson structure whose quantization may be constructed in terms of the corresponding quantum group. When the quantum parameter is a root of unity, this quantization carries a central subalgebra isomorphic to the algebra of functions on the classical character variety. In this talk I will describe a procedure which allows one to obtain Azumaya algebras via quantum Hamiltonian reduction. As an ...

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## Multi angle  Arithmetic of rank one local systems Esnault, Hélène (Auteur de la Conférence) | CIRM (Editeur )

Joint with Moritz Kerz. We study arithmetic subvarieties of the character variety of normal complex varieties defined over a field of finite type.

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## Multi angle  $T$-structures from categorical actions Koppensteiner, Clemens (Auteur de la Conférence) | CIRM (Editeur )

$T$-structures on derived categories of coherent sheaves are an important tool to encode both representation-theoretic and geometric information. Unfortunately there are only a limited amount of tools available for the constructions of such $t$-structures. We show how certain geometric/categorical quantum affine algebra actions naturally induce $t$-structures on the categories underlying the action. In particular we recover the categories of exotic sheaves of Bezrukavnikov and Mirkovic.
This is joint work with Sabin Cautis.
$T$-structures on derived categories of coherent sheaves are an important tool to encode both representation-theoretic and geometric information. Unfortunately there are only a limited amount of tools available for the constructions of such $t$-structures. We show how certain geometric/categorical quantum affine algebra actions naturally induce $t$-structures on the categories underlying the action. In particular we recover the categories of ...

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## Multi angle  Cohomology jump loci and singularities Budur, Nero (Auteur de la Conférence) | CIRM (Editeur )

Cohomology jump loci of local systems generalize the Milnor monodromy eigenvalues. We address recent progress on the local and global structure of cohomology jump loci. More generally, given an object with a notion of cohomology theory, how can one describe all its deformations subject to cohomology constraints? We give an answer in terms of differential graded Lie algebra pairs. This is joint work with Botong Wang.

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## Multi angle  A strong hyperbolicity property of locally symmetric varieties Brunebarbe, Yohan (Auteur de la Conférence) | CIRM (Editeur )

We show that all subvarieties of a quotient of a bounded symmetric domain by a sufficiently small arithmetic group are of general type.

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## Multi angle  Fourier-Mukai partners of canonical covers in positive characteristic Tirabassi, Sofia (Auteur de la Conférence) | CIRM (Editeur )

We show that surfaces arising as canonical covers of Enriques and bielliptic surfaces do not have any non-trivial Fourier-Mukai partner, extending result of Sosna for complex surfaces. This is a joint work with K. Honigs and L. Lombardi.

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## Multi angle  $D$-modules and $p$-curvatures Esnault, Hélène (Auteur de la Conférence) | CIRM (Editeur )

We show relations between rigidity of connections in characteristic 0 and nilpotency of their $p$-curvatures (a consequence of a conjecture by Simpson and of a generalization of Grothendieck's $p$-curvature conjecture).
Work in progress with Michael Groechenig.

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## Multi angle  Semi-infinite Hodge structures in noncommutative geometry Shklyarov, Dmytro (Auteur de la Conférence) | CIRM (Editeur )

Homological mirror symmetry asserts that the connection, discovered by physicists, between a count of rational curves in a Calabi-Yau manifold and period integrals of its mirror should follow from an equivalence between the derived Fukaya category of the first manifold and the derived category of coherent sheaves on the second one. Physicists' observation can be reformulated as, or rather upgraded to, a statement about an isomorphism of certain Hodge-like data attached to both manifolds, and a natural first step towards proving the above assertion would be to try to attach similar Hodge-like data to abstract derived categories. The aim of the talk is to report on some recent progress in this direction and illustrate the approach in the context of what physicists call Landau-Ginzburg B-models.
Homological mirror symmetry asserts that the connection, discovered by physicists, between a count of rational curves in a Calabi-Yau manifold and period integrals of its mirror should follow from an equivalence between the derived Fukaya category of the first manifold and the derived category of coherent sheaves on the second one. Physicists' observation can be reformulated as, or rather upgraded to, a statement about an isomorphism of certain ...

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## Multi angle  The coherent Satake category Williams, Harold (Auteur de la Conférence) | CIRM (Editeur )

The geometric Satake equivalence identifies the Satake category of a reductive group $G$ - that is, the category of equivariant perverse sheaves on the affine Grassmannian $G_{rG}$ - with the representation category of its Langlands dual group $G^∨$. While the Satake category is topological in nature, it has a poorly understood algebro-geometric cousin: the category of perverse coherent sheaves on $G_{rG}$. This category is not semi-simple and its monoidal product is not symmetric. We show however that it is rigid and admits renormalized r-matrices similar to those appearing in the theory of quantum loop or KLR algebras. Applying the framework developed by Kang-Kashiwara-Kim-Oh in their proof of the dual canonical basis conjecture, we use these results to show that the coherent Satake category of $GL_n$ is a monoidal cluster categorification in the sense of Hernandez-Leclerc. This clarifies the physical meaning of the coherent Satake category: simple perverse coherent sheaves correspond to Wilson-’t Hooft operators in $\mathcal{N} = 2$ gauge theory, just as simple perverse sheaves correspond to ’t Hooft operators in $\mathcal{N} = 4$ gauge theory following the work of Kapustin-Witten. Our results also explain the appearance of identical quivers in the work of Kedem-Di Francesco on $Q$-systems and in the context of BPS quivers. More generally, our construction of renormalized r-matrices works in any chiral $E_1$-category, providing a new way of understanding the ubiquity of cluster algebras in $\mathcal{N} = 2$ field theory: the existence of renormalized r-matrices, hence of iterated cluster mutation, is a formal feature of such theories after passing to their holomorphic-topological twists. This is joint work with Sabin Cautis (arXiv:1801.08111).
The geometric Satake equivalence identifies the Satake category of a reductive group $G$ - that is, the category of equivariant perverse sheaves on the affine Grassmannian $G_{rG}$ - with the representation category of its Langlands dual group $G^∨$. While the Satake category is topological in nature, it has a poorly understood algebro-geometric cousin: the category of perverse coherent sheaves on $G_{rG}$. This category is not semi-simple and ...

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## Multi angle  Cayley-Bacharach theorems with excess vanishing Lazarsfeld, Robert (Auteur de la Conférence) | CIRM (Editeur )

A classical result usually attributed to Cayley and Bacharach asserts that if two plane curves of degrees c and d meet in cd points, then any curve of degree (c + d - 3) passing through all but one of these points must also pass through the remaining one. In the late 1970s, Griffiths and Harris showed that this is a special case of a general result about zero-loci of sections of a vector bundle. Inspired by a recent paper of Mu-Lin Li, I will describe a generalization allowing for excess vanishing. Multiplier ideals enter the picture in a natural way. Time permitting, I will also explain how a result due to Tan and Viehweg leads to statements of Cayley-Bacharach type for determinantal loci. This is joint work with Lawrence Ein.
A classical result usually attributed to Cayley and Bacharach asserts that if two plane curves of degrees c and d meet in cd points, then any curve of degree (c + d - 3) passing through all but one of these points must also pass through the remaining one. In the late 1970s, Griffiths and Harris showed that this is a special case of a general result about zero-loci of sections of a vector bundle. Inspired by a recent paper of Mu-Lin Li, I will ...

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