
SCIENTIFIC PROGRAMS AND ACTIVITIES 

September 21, 2021  
Thematic Program on the Geometry of String
Theory

String Theory Thematic Year home page  High Energy Physics Seminars  Audio Links 
Perimeter Institute String Seminars  Symplectic Geometry Seminars  GuelphWaterloo Gravity Seminars 
Jan. 7 
Atsushi Takahashi, RIMS, Kyoto Matrix Factorizations and Representations of Quivers 
Jan. 27 
Jaemo Park, Pohang U Supertwistor Orbifolds: Gauge Theory Amplitudes and Topological Strings 
Jan. 27 
Amihay Hanany, MIT Quivers for Metrics 
Jan. 31 
Alexei Gorodentsev, ITEP, Moscow Tstabilities on triangulated categories 
Feb. 3 
Cobi Sonnenschein, Tel Aviv U More on the noncritical gauge/gravity duality 
Feb. 10 
Ofer Aharony, Weitzmann Inst. Gravitational phase transitions from a field theory perspective 
Feb. 10 
Matthias Gaberdiel, Zurich, ETH Topological permutation branes 
Mar. 10 
Yan Soibelman, Kansas State Mirror symmetry and nonarchimedean analytic geometry 
Mar. 14 
A M Semikhatov, Lebedev Inst., Moscow Nonsemisimple Verlinde algebras and quantum groups 
Mar. 18 
Anirban Basu, Chicago The M2M5 Brane System and a Generalized Nahm's Equation 
Mar. 18 
Juan Cascales, Universidad Autonoma de MadridCSIC Holographic dual of the Standard Model on the throat 
Apr. 11 
Duco van Straten, U Gutenberg An Index theorem for Matrix Factorizations 
Apr. 14 
Piljin Yi, KIAS Closed Strings and Unstable DBrane Systems 
June 16 
Don Marolf, UCSB Clarifying holographic charges 
June 16 
Mark Van Raamsdonk, UBC Phase diagrams for large N gauge theories on compact spaces 
Wed., Sept. 22  Marco Gualtieri, Fields Institute An introduction to generalized geometry Abstract: I will provide an introduction to the new field of generalized geometry, initiated by Hitchin (math.DG/0209099) and developed in my thesis (math.DG/0401221). I will concentrate mainly on generalized complex geometry, which is a unification of complex and symplectic geometry. I will make some comments about the implications for mirror symmetry. If time permits I will speak about generalized Riemannian and Kahler geometry. 
Mon., Oct. 4 
Fyodor Malikov, University of Southern
California / Fields Institute Algebras of chiral differential operators and the Courant bracket Abstract: This talk is intended to serve a twofold purpose: first, to give an introduction to sheaves of vertex algebras on smooth manifolds and, second, to explain that vertex algebras is a natural framework for the Courant brackets. 
Wed., Oct. 6 
Ke Zhu, Fields Institute Degeneration of the moduli space of Jholomorphic discs and Legendrian contact homology Abstract: In this paper, I study the degeneration of the moduli space of $J$holomorphic discs in the cotangent bundle ending on an exact multicovering Lagrangian submanifold. The main theorem establishes an embedding of the trivalent gradient flow tree moduli space induced from the exact multicovering Lagrangian submanifold into the above $J$holomorphic disc moduli space, provided the Lagrangian submanifold is sufficiently close to the zero section and satisfies some generic conditions. As an application, I use the degeneration to show the combinatorial braid invariants defined by Ng is isomorphic to the Legendrian contact homology in the 1jet space $J^1(T^2)$ for the Legendrian submanifold arising from the braid's monodromy. 
Wed.,Oct. 13 
Ionut CiocanFontanine, University
of Minnesota / Fields Institute A generalisation of the HoriVafa Conjecture Abstract: A few years ago, Hori and Vafa conjectured that the LandauGinzburg model mirror to the nonlinear sigmamodel on a Grassmannian can be obtained by "symmetrizing" the LandauGinzburg model mirror to a product of projective spaces. In particular, this conjecture predicts a precise relation between the Jfunctions (generating functions for certain genus zero GromovWitten invariants) of these varieties. This talk will describe joint work with Aaron Bertram and Bumsig Kim in which we argue that the appropriate general context for the above relationship is that of twisted GW invariants of abelian and nonabelian GIT quotients. As a concrete example, I will present a theorem giving closed formulas for the Jfunctions of all isotropic partial flag varieties of classical type. 
Mon., Oct. 18 
F. Malikov, University of Southern
California / Fields Institute Algebras of chiral differential operators and the Courant bracket (part 2) 
Wed., Oct. 20 
Paul Horja, Fields Institute Toric DeligneMumford stacks and mirror symmetry Abstract: Toric DeligneMumford stacks have been studied recently by Borisov, Chen and Smith. As it is the case with the usual toric varieties, the combinatorial tools provide good testing methods in algebraic geometry. I will present some results in the context of homological mirror symmetry. This is joint work with Lev Borisov. 
Mon., Oct. 25 
Kai Behrend,
University of British Columbia / Fields Institute On some aspects of the de Rham cohomology of stacks Abstract: I will start by reviewing the definition of the de Rham cohomology of a stack. By "stack" I mean an Artin stack in the differentiable, holomorphic, or algebraic categories. The standard "Cech  de Rham complex" used to calculate/define the cohomology is rather large, as the de Rham complex does not consist of vector bundles (in the manifold case: the cotangent bundle and its exterior powers) but so called "big sheaves". We attempt to construct a smaller Cech  de Rham complex for stacks, which is defined in terms of vector bundles over the stack. To do this, we require an extra structure on the stack. We call this structure a "flat connection". The notion of flat connection on a stack generalizes the notions of flat connection on vector bundles and on gerbes. 
Wed., Oct. 27 
JeanYves Welschinger, Ecole Normale
Superieure de Lyon / Fields Institute Invariants of real symplectic 4manifolds out of reducible and cuspidal pseudoholomorphic curves 
Mon., Nov. 1 
Robert Penner, University of Southern
California / Fields Institute On a cell decomposition of a blowup of the DeligneMumford compactification 
Fri., Nov. 5 
Eric Zaslow, Northwestern University
/ Fields Institute Affine Manifolds, Torus Fibrations and the YVertex Abstract: CalabiYau threefolds have been conjectured to have a specialLagrangian torus fibration in an asymptotic sense near the large complex structure limit point of moduli space. "At" the limit, the fibers should become flatter and smaller while the threefold collapses to the base of the fibration, which acquires an affine structure. The locus (in the base) of singular fibers conjecturally becomes a trivalent graph, generically. I will discuss the affine geometry of real threefolds and prove the existence of a Ricciflat metric on a specialLagrangian torus fibration in the neighborhood of a trivalent vertex of the singularity locus. 
Mon., Nov. 8 
WeiDong Ruan, University of Illinois
at Chicago / Fields Institute Deformations of integral coisotropic submanifolds in symplectic manifold 
Nov. 10  29  No seminars 
Wed., Dec. 1 
Joint Geometry / String Theory seminar Vladimir Fock, ITEP Cluster varieties in everyday life 
Wed., Dec. 1 
Jim Bryan, UBC The local GromovWitten theory of curves Abstract: We study the equivariant GromovWitten theory of a rank two vector bundle N over a nonsingular curve X of genus g. This theory generalizes the local CalabiYau theory of X. We develop a gluing theory for the partition functions by degenerating the base curve. We show that the gluing relations, along with our explicit computations of a few basic partition functions, recursively determine all the invariants. In the case where N is the direct sum of two copies of a square root of the canonical bundle, equipped with the antidiagonal C^* action, the partition function is a Qdeformation of the classical Hurwitz formula for counting unramified covers. We formulate an equivariant version of the GromovWitten/DonaldsonThomas correspondence and discuss it for the case of N. 
Mon., Dec. 6 
No seminar 
Wed., Dec. 8  Alexei Bondal, Steklov Mathemaical
Institute / Fields Institute Mirror symmetry via constructible sheaves Abstract: We will descuss an approach to homological mirror symmetry via constructible sheaves, which allow to prove and to better undestand it for a class of toric varieties. 
Dec. 13Jan. 5  No seminars 