Surfacehedra and the Binary Positive Geometry of Particle and “String” Amplitudes
Speaker: Nima Arkani-Hamed, IAS Title: Surfacehedra and the Binary Positive Geometry of Particle and “String” Amplitudes
12 events found.
What do bounding chains look like, and why are they related to linking numbers?
Abstract: Gromov-Witten invariants count pseudo-holomorphic curves on a symplectic manifold passing through some fixed points and submanifolds. Similarly, open Gromov-Witten invariants are supposed to count disks with boundary on a Lagrangian, but in most cases such counts are not independent of some choices as we would wish. Motivated by Fukaya’11, J. Solomon and S. Tukachinsky constructed […]
Symmetry types in QFT and the CRT theorem
Title: Symmetry types in QFT and the CRT theorem Abstract: I will discuss ideas around symmetry and Wick rotation contained in joint work with Mike Hopkins (https://arxiv.org/abs/1604.06527). This includes general symmetry types for relativistic field theories and their Wick rotation. I will then indicate how the basic CRT theorem works for general symmetry types, focusing […]
The number of n-queens configurations
Speaker: Michael Simkin, Harvard CMSA Title: The number of n-queens configurations Abstract: The n-queens problem is to determine Q(n), the number of ways to place n mutually non-threatening queens on an n x n board. The problem has a storied history and was studied by such eminent mathematicians as Gauss and Polya. The problem has also […]
Applications of instantons, sphalerons and instanton-dyons in QCD
Title: Applications of instantons, sphalerons and instanton-dyons in QCD Abstract: I start with a general map of gauge topology, including monopoles, instantons and instanton-dyons. Then comes reminder of the “topological landscape”, the minimal energy gauge field configurations, as a function of Chern-Simons number Ncs and r.m.s. size. It includes “valleys” at integer Ncs separated by […]
The many phases of a cell
Abstract: I will begin by introducing an emerging paradigm of cellular organization – the dynamic compartmentalization of biochemical pathways and molecules by phase separation into distinct and multi-phase condensates. Motivated by this, I will discuss two largely orthogonal problems, united by the theme of phase separation in multi-component and chemically active fluid mixtures. 1. I will […]
9/23/2021 Interdisciplinary Science Seminar
Title: The number of n-queens configurations Abstract: The n-queens problem is to determine Q(n), the number of ways to place n mutually non-threatening queens on an n x n board. The problem has a storied history and was studied by such eminent mathematicians as Gauss and Polya. The problem has also found applications in fields […]
9/24/2021 General Relativity Seminar
Title: On the Observable Shape of Black Hole Photon Rings Abstract: The photon ring is a narrow ring-shaped feature, predicted by General Relativity but not yet observed, that appears on images of sources near a black hole. It is caused by extreme bending of light within a few Schwarzschild radii of the event horizon and […]
Stability and convergence issues in mathematical cosmology
Member Seminar Speaker: Puskar Mondal Title: Stability and convergence issues in mathematical cosmology Abstract: The standard model of cosmology is built on the fact that while viewed on a sufficiently coarse-grained scale the portion of our universe that is accessible to observation appears to be spatially homogeneous and isotropic. Therefore this observed `homogeneity and isotropy’ of our […]
Convexity of Charged Operators in CFTs and the Weak Gravity Conjecture
Abstract: In this talk I will introduce a particular formulation of the Weak Gravity Conjecture in AdS space in terms of the self-binding energy of a particle. The holographic CFT dual of this formulation corresponds to a certain convex-like structure for operators charged under continuous global symmetries. Motivated by this, we propose a conjecture that this […]
9/28/2021 Combinatorics, Physics and Probability Seminar
Title: The hypersimplex and the m=2 amplituhedron Abstract: I’ll discuss a curious correspondence between the m=2 amplituhedron, a 2k-dimensional subset of Gr(k, k+2), and the hypersimplex, an (n-1)-dimensional polytope in R^n. The amplituhedron and hypersimplex are both images of the totally nonnegative Grassmannian under some map (the amplituhedron map and the moment map, respectively), but […]
The Mirror Clemens-Schmid Sequence
Abstract: I will present a four-term exact sequence relating the cohomology of a fibration to the cohomology of an open set obtained by removing the preimage of a general linear section of the base. This exact sequence respects three filtrations, the Hodge, weight, and perverse Leray filtrations, so that it is an exact sequence of mixed […]