A classical result of Turaev identifies the skein algebra of the annulus with the algebra of symmetric functions in infinitely many variables. Queffelec and Roze categorified this using annular webs and foams. I will recall their construction and compute explicit symmetric functions and their categorical analogues for some links. As an application, I will describe spectral sequences computing categorical invariants … Read More

Abstract: Virasoro constraints are omnipresent in enumerative geometry. Recently, Kontsevich and Soibelman introduced a generalization of Virasoro constraints in the form of Airy structures. It can also be understood as an abstract framework underlying the topological recursion of Chekhov, Eynard and Orantin. In this talk I will explain how the triumvirate of Virasoro constraints, Airy structures and topological recursion can … Read More

Abstract: Calabi-Yau manifolds have played a central role in both string theory and mathematics for decades, but in spite of this no Ricci-flat metric on a compact non-toroidal Calabi-Yau manifold is known. I will discuss a new physically motivated approach toward the determination of such metrics for K3 surfaces. The key remaining step is the determination of a BPS spectrum … Read More

This is a joint work with A. Oblomkov exploring the relation between the HOMFLY-PT link homology and coherent sheaves over the Hilbert scheme of points on C^2. We consider a special object in the 2-category related to the Hilbert scheme of n points on C^2. We define a homomorphism from the braid group on n strands to the monoidal category … Read More

Abstract: I will describe joint work with Ciprian Manolescu on constructing an analogue of instanton Floer homology replacing the group SU(2) by SL(2,C). Having failed to do so using the standard Floer theoretic tools of gauge theory and symplectic topology, we turned to sheaf theory to produce an invariant. After describing our approach, I will discuss some features of this … Read More

Basing on the representation theory of quantum toroidal algebras we propose a generalization of the refined topological vertex formalism incorporating additional “Higgsed” vertices and lines apparently corresponding to refined Lagrangian branes. We find rich algebraic structure associated to brane diagrams incorporating the new vertices and lines. In particular, we build the screening charges associated to W-algebras of types gl(n) and … Read More

Abstract: 3 dimensional N=4 supersymmetric quantum field theories have two distinguished topological twists, called Higgs and Coulomb (though we periodically get confused about which is which). These two twists manifest very interesting mathematical objects in Lie theory and algebraic geometry, which don’t seem to obviously be related, except through this bridge in QFT. I’ll do my best to explain what … Read More

Abstract: Both the Higgs bundle moduli space and the moduli space of flat connections have a natural stratification induced by a C* action. In both of these stratifications, each stratum is a holomorphic fibration over a connected component of complex variations of Hodge structure. While the nonabelian Hodge correspondence provides a homeomorphism between Higgs bundles and flat connections, this homeomorphism … Read More

Abstract: Wilson loops are important observables in gauge theory. In this talk, we study half-BPS Wilson loops of a large class of five dimensional supersymmetric quiver gauge theories with 8 supercharges, in a nontrivial instanton background. The Wilson loops are codimension 4 defects of the quiver gauge theory, and their interaction with self-dual instantons is captured by a 1d ADHM … Read More