Today

  • Kobayashi-Hitchin correspondences for harmonic bundles and monopoles

    Virtual

    Speaker: Takuro Mochizuki (Kyoto University) Title: Kobayashi-Hitchin correspondences for harmonic bundles and monopoles Abstract:  In 1960's, Narasimhan and Seshadri discovered the equivalence between irreducible unitary flat bundles and stable bundles of degree $0$ on compact Riemann surfaces. In 1980's, Donaldson, Uhlenbeck and Yau generalized it to the equivalence between irreducible Hermitian-Einstein bundles and stable bundles on smooth […]

  • Virtual Coulomb branch and quantum K-theory

    Virtual

    Abstract: In this talk, I will introduce a virtual variant of the quantized Coulomb branch constructed by Braverman-Finkelberg-Nakajima, where the convolution product is modified by a virtual intersection. The resulting virtual Coulomb branch acts on the moduli space of quasimaps into the holomorphic symplectic quotient T^*N//G. When G is abelian, over the torus fixed points, this […]

  • CMSA-QMMP-02.10.2022-1544x2048-1

    The global structure of the Standard Model and new nonperturbative processes

    Virtual

    Speaker: Mohamed Anber (Durham University) Title: The global structure of the Standard Model and new nonperturbative processes Abstract: It is well-established that the Standard Model (SM) of particle physics is based on su(3)Xsu(2)Xu(1) Lie-algebra. What is less appreciated, however, is that SM accommodates a Z_6 1-form global symmetry.  Gauging this symmetry, or a subgroup of it, changes […]

  • CMSA-QMMP-02.09.2022-1544x2048-1

    On the absence of global anomalies of heterotic string theories

    Virtual

    Speaker: Yuji Tachikawa (Kavli IPMU, U Tokyo) Title: On the absence of global anomalies of heterotic string theories Abstract: Superstring theory as we know it started from the discovery by Green and Schwarz in 1984 that the perturbative anomalies of heterotic strings miraculously cancel. But the cancellation of global anomalies of heterotic strings remained an open […]

  • CMSA-NTM-Seminar-02.09.2022-1553x2048

    Toward Demystifying Transformers and Attention

    Virtual

    https://youtu.be/MSw8HV0eHo8 Speaker: Ben Edelman, Harvard Computer Science Title: Toward Demystifying Transformers and Attention Abstract: Over the past several years, attention mechanisms (primarily in the form of the Transformer architecture) have revolutionized deep learning, leading to advances in natural language processing, computer vision, code synthesis, protein structure prediction, and beyond. Attention has a remarkable ability to enable the […]

  • Tetrahedron instantons and M-theory indices

    Virtual

    Colloquium Speaker: Wenbin Yan (Tsinghua University) Title: Tetrahedron instantons and M-theory indices Abstract: We introduce and study tetrahedron instantons. Physically they capture instantons on $\mathbb{C}^{3}$ in the presence of the most general intersecting codimension-two supersymmetric defects. In this talk, we will review instanton moduli spaces, explain the construction, moduli space and partition functions of tetrahedron instantons. We […]

  • SYZ Conjecture beyond Mirror Symmetry

    Virtual

    Abstract: Strominger-Yau-Zaslow conjecture is one of the guiding principles in mirror symmetry, which not only predicts the geometric structures of Calabi-Yau manifolds but also provides a recipe for mirror construction. Besides mirror symmetry, the SYZ conjecture itself is the holy grail in geometrical analysis and closely related to the behavior of the Ricci-flat metrics. In this talk, […]

  • Quantum Oscillations of Electrical Resistivity in an Insulator

    Virtual

    Speaker: Lu Li (U Michigan) Title: Quantum Oscillations of Electrical Resistivity in an Insulator Abstract: In metals, orbital motions of conduction electrons are quantized in magnetic fields, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators, in which all the electrons are localized. Here we report a notable exception […]

  • Learning and inference from sensitive data

    Virtual

    Speaker: Adam Smith (Boston University) Title: Learning and inference from sensitive data Abstract: Consider an agency holding a large database of sensitive personal information—say,  medical records, census survey answers, web searches, or genetic data. The agency would like to discover and publicly release global characteristics of the data while protecting the privacy of individuals’ records. I will discuss recent (and not-so-recent) results on this problem with […]

  • CMSA-Algebraic-Geometry-in-String-Theory-02.01.2022

    Curve-counting with fixed domain (“Tevelev degrees”)

    Virtual

    Abstract: We will consider the following problem: if (C,x_1,…,x_n) is a fixed general pointed curve, and X is a fixed target variety with general points y_1,…,y_n, then how many maps f:C -> X in a given homology class are there, such that f(x_i)=y_i? When considered virtually in Gromov-Witten theory, the answer may be expressed in terms of […]

  • The smooth closing lemma for area-preserving surface diffeomorphisms

    Virtual

    Speaker: Boyu Zhang, Princeton University Title: The smooth closing lemma for area-preserving surface diffeomorphisms Abstract: In this talk, I will introduce the smooth closing lemma for area-preserving diffeomorphisms on surfaces. The proof is based on a Weyl formula for PFH spectral invariants and a non-vanishing result of twisted Seiberg- Witten Floer homology. This is joint work […]

  • CMSA-NTM-Seminar-12.15.21

    Unreasonable effectiveness of the quantum complexity view on quantum many-body physics

    Virtual

    https://youtu.be/wKCgR3aFpnc Speaker: Anurag Anshu, Department of EECS & Challenge Institute for Quantum Computation, UC Berkeley Title: Unreasonable effectiveness of the quantum complexity view on quantum many-body physics Abstract: A central challenge in quantum many-body physics is to estimate the properties of natural quantum states, such as the quantum ground states and Gibbs states. Quantum Hamiltonian complexity […]