Today

  • Extreme Black Holes: Anabasis and Accidental Symmetry

    Virtual

      https://youtu.be/USKZjJ8_LI0   Speaker: Achilleas Porfyriadis, Harvard Black Hole Initiative Title: Extreme Black Holes: Anabasis and Accidental Symmetry Abstract: The near-horizon region of black holes near extremality is universally AdS_2-like. In this talk I will concentrate on the simplest example of  AdS_2 x S^2 as the near-horizon of (near-)extreme Reissner-Nordstrom. I will first explain the SL(2)transformation properties of the spherically […]

  • Holographic Cone of Average Entropies and Universality of Black Holes

    Virtual

    Speaker: Bartek Czech, Tsinghua University Title: Holographic Cone of Average Entropies and Universality of Black Holes Abstract:  In the AdS/CFT correspondence, the holographic entropy cone, which identifies von Neumann entropies of CFT regions that are consistent with a semiclassical bulk dual, is currently known only up to n=5 regions. I explain that average entropies of p-partite subsystems can […]

  • CMSA-Algebraic-Geometry-in-String-Theory-02.22.2022

    Higgs-Coulomb correspondence in abelian GLSM

    Virtual

    Abstract: We construct a certain type of Gauged Linear Sigma Model quasimap invariants that generalize the original ones and are easier to compute. Higgs-Coulomb correspondence provides identification of generating functions of our invariants with certain analytic functions that can be represented as generalized inverse Mellin transforms. Analytic continuation of these functions provides wall-crossing results for GLSM […]

  • CMSA-QMMP-02.17.2022-1544x2048

    Spin-cobordisms, surgeries and fermionic modular bootstrap

    Virtual

    Speaker: Andrea Grigoletto (SISSA & INFN) Title: Spin-cobordisms, surgeries and fermionic modular bootstrap Abstract: ‘tHooft anomalies of anomalous systems can be described via anomaly inflow by invertible theories living in one dimension higher. Thanks to this it is possible to provide a general method to determine modular transformations of anomalous 2d fermionic CFTs with general discrete symmetry […]

  • CMSA-NTM-Seminar-02.16.2022-1553x2048

    Bootstrapping hyperbolic manifolds

    Virtual

    https://youtu.be/updzX0XPYU4 Speaker: James Bonifacio, Cambridge DAMTP Title: Bootstrapping hyperbolic manifolds Abstract: Hyperbolic manifolds are a class of Riemannian manifolds that are important in mathematics and physics, playing a prominent role in topology, number theory, and string theory. Associated with a given hyperbolic metric is a sequence of numbers corresponding to the discrete eigenvalues of the […]

  • CMSA-QMMP-02.16.2022-1544x2048

    Topological Quantum Gravity and the Ricci Flow – Part I

    Virtual

    Speaker: Petr Hořava (UC Berkeley) Title: Topological Quantum Gravity and the Ricci Flow – Part I Abstract: In this sequence of talks, I will describe our work with Alexander Frenkel and Stephen Randall, in which we presented a novel topological quantum gravity, relating three previously unrelated fields:  Topological quantum field theories (of the cohomological type), the […]

  • 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 […]