Colloquia & Seminars

Title: Index from a point

Differential Geometry and Physics Seminar Speaker: Monica Jinwoo Kang, Texas A&M University Title: Index from a point Abstract: We argue that protected data of 4d N=2 SCFTs admits a purely algebro-geometric characterization. We conjecture that both the Macdonald index (and hence the Schur index) and the Higgs branch are encoded by a bifiltered affine scheme determined by OPE nilpotency and decoupling relations. Focusing on Argyres–Douglas theories, where the Higgs branch is a point, we show that this geometric construction suffices to reconstruct the full Macdonald index. This is based on recent works with Craig Lawrie and Jaewon Song.

Title: On E7+1/2 gauge theory

Differential Geometry and Physics Seminar Speaker: Yinan Wang, Peking University Title: On E7+1/2 gauge theory Abstract: We propose that an exotic gauge theory based on the intermediate Lie algebra E7+1/2 naturally appears in the landscape of 6d F-theory. We give strong evidence of this proposal with 6d anomaly cancellation, dual M-theory geometry and elliptic genus of the single-string worldsheet CFT. 

Title: Algebra Seminar

Algebra Seminar  

Title: Lie algebra cohomology and Seiberg-Witten theory

Member Seminar Speaker: Ahsan Khan, Harvard CMSA Title: Lie algebra cohomology and Seiberg-Witten theory Abstract: I will discuss how a certain (relative) Lie algebra cochain complex categorifies the Schur index of N=2 supersymmetric gauge theory. For the special case of Seiberg-Witten theory I will provide a conjectured description of this cohomology.

Title: On the p-curvature of quantum connections of CY threefolds

Quantum Field Theory and Physical Mathematics Seminar Speaker: Shaoyun Bai (MIT) Title: On the p-curvature of quantum connections of CY threefolds Abstract: The small quantum connection of Calabi-Yau varieties has integral coefficients, thus admits reduction mod a prime number p. A fundamental invariant associated with flat connections over characteristic p is the p-curvature, which lies at the heart of study of algebraic differential equations. I will explain how to identify the p-curvature of quantum connection of any compact Calabi-Yau threefold with the quantum Steenrod operation, thereby providing a modular description of the p-curvature in this setting. I will also discuss the role of BPS invariants and the mirror symmetry context. This is based on joint work with Jae...

Title: Phase Transition to Chaos in Complex Ecosystems with Non-reciprocal Interactions

Colloquium Speaker: Pankaj Metha, Boston University Title: Phase Transition to Chaos in Complex Ecosystems with Non-reciprocal Interactions Abstract: Nonreciprocal interactions between microscopic constituents can profoundly shape the large-scale properties of complex systems. In this pedagogical chalk talk, I will discuss recent work from our group on phase transitions and chaos in high-dimensional ecosystems with non-reciprocal interactions. Our approach builds on a generalization of MacArthur's consumer-resource model that incorporates asymmetric interactions between species and resources. I will highlight rich connections between this problem and the mathematics of disordered systems (cavity method and DMFT), random matrix theory, and constrained optimization.

Title: Solitonic Symmetry: Cohomology with TFT Coefficients

Geometry and Quantum Theory Seminar Speaker: Sanjay Raman, Harvard Title: Solitonic Symmetry: Cohomology with TFT Coefficients Abstract: We review the formalism of https://arxiv.org/pdf/2307.00939, which develops the theory of solitonic symmetry in quantum field theory. The algebraic structure of solitonic symmetry is determined by the fusion of topological functionals in a given path-integral formulation of topological field theory, and acts generically on topological defects determined by homotopy classes of maps to a “space of fields.” We will argue that the structure of solitonic symmetry in a theory with field space (Y) assembles into what looks like the cohomology of (Y) with coefficients in TFTs. We study this formalism in examples and show in particular that the maximal invertible solitonic subsymmetry reduces to...

Title: CMSA Q&A Seminar: James Eldred Pascoe, Drexel University

CMSA Q&A Seminar Speaker: James Eldred Pascoe, Drexel University Title: (What is) The tracial fundamental group and free universal monodromy? Abstract: We introduce the tracial fundamental group to classify the analytic continuation of functions that are locally behave like the trace of natural matrix valued functions. While globally defined natural matrix-valued functions (known as free noncommutative functions, which roughly locally are defined by noncommutative power series) satisfy universal monodromy, we show that these tracial free functions exhibit a rigid but nontrivial structure governed by the aforementioned group. We prove that the tracial fundamental group is always a torsion-free, divisible abelian group, standing in sharp contrast to the non-abelian fundamental groups of classical domains.

Title: ReLU and Softplus neural nets as zero-sum, turn-based, stopping games

New Technologies in Mathematics Seminar Speaker: Yiannis Vlassopoulos, Athena Research Center Title: ReLU and Softplus neural nets as zero-sum, turn-based, stopping games Abstract: Neural networks are for the most part treated as black boxes. In an effort to begin elucidating the mathematical structure they encode, we will explain how ReLU neural nets can be interpreted as zero-sum turn-based, stopping games. The game runs in the opposite direction to the net. The input to the net is the terminal reward of the game, the output of the net is the value of the game at its initial states. The bias at each neuron is used to define the reward and the weights are used to define state-transition probabilities. One player...

Title: Differential Geometry and Physics Seminar

Differential Geometry and Physics Seminar Speaker: Gabor Szekelyhidi, Northwestern University

Title: Algebra Seminar

Algebra Seminar  

Title: Member Seminar

Member Seminar Speaker: Lorenzo Riva

Title: Quantum Field Theory and Physical Mathematics Seminar

Quantum Field Theory and Physical Mathematics Seminar Speaker: Shaoyun Bai, Massachusetts Institute of Technology

Title: Geometry and Quantum Theory Seminar

Geometry and Quantum Theory Seminar Speakers: Max Hübner and Saman Habibi Esfahani

Title: CMSA Q&A Seminar

CMSA Q&A Seminar Details TBA