Date | Speaker | Title | Abstract | Location |
---|---|---|---|---|

9.2.17 2pm |
G. Gabadadze (NYU) | The Cost to Cancel the Cosmological Constant | After a brief review of the cosmological constant problem, and failures to solve it, I will discuss an unusual framework of canceling the cosmological constant, and will talk about massive gravity and its extensions as a way to get dark energy in that framework. | Salmon Lecture Theatre |

9.2.17 3:30pm |
Yuri Tschinkel (NYU and Simons Foundation) | Rational and irrational varieties | I will discuss recent advances in the theory of Fano varieties over nonclosed fields (joint with B. Hassett, A. Kresch, and A. Pirutka). | Salmon Lecture Theatre |

9.2.17 5pm |
A. Okounkov (Columbia University) | Geometric Construction of Bethe eigenfunctions | A fundamental discovery of Nekrasov and Shatashvili equates quantum K-theory of a Nakajima quiver variety (as a commutative ring) with Bethe equations for a certain quantum affine Lie algebra. I will explain how to go make the next step and find the corresponding Bethe eigenfunctions and, more generally, solutions to qKZ and dynamical difference equations. This is a joint work with Mina Aganagic. | Synge Lecture Theatre |

10.2.17 2pm |
M. Kontsevich (IHES) | Algebra and geometry of topological recursion | Topological recursion proposed 10 years ago by B.Eynard and N.Orantin, starts with а spectral curve endowed with some additional data, and produces an infinite family of polydifferential forms on powers of the curve, via а complicated recursive procedure involving residues. It is important because it gives a way to effectively calculate correlation functions in matrix models, and string partition function for noncompact Calabi-Yau 3-folds. One of features of topological recursion is that it produces symmetric tensors via a priori non-symmetric formulas. I'll talk about my recent work with Y.Soibelman where we uncovered the hidden reason behind this symmetry, based on Lie algebras of quadratic Hamiltonians. | Maxwell Lecture Theatre |

10.2.17 3:30pm |
N. Nekrasov (SCGP) | The Magnificent Four | In studying gauge theories in various dimensions one comes across various enumerative problems: counting of holomorphic curves in Calabi-Yau manifolds, intersection theory on moduli spaces of instantons, limit shapes for random Young diagrams in two and three dimensions. The latter problem is related to dimer models and the models of crystal melting. We shall report on the recent developments in four dimensions, the ultimate dimension for crystal melting coming from supersymmetric gauge theory. The string theory context of the problem is the counting the bound states of D0 branes in the presence of the D8 brane and a B-field. The random configurations are tilings of the 3-space by four types of squashed cubes. The similar problem of D0-D6 brane counting led to the partition function which was conjectured in 2004 to be given by the Witten index of 11d supergravity. The conjecture was proven in 2015 by A.Okounkov. I will present the conjecture on the partition function of the new model. It hints at the twelve-dimensional origin of the problem. | Maxwell Lecture Theatre |

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