Fall, 2020

Fall, 2020

  • Speaker Bin Gui, Rutgers University
    • Title Convergence of sewing conformal blocks
    • Time 11/6/2020, Friday, 12:00 (Eastern Time)
    • Location Zoom link above
    • Abstract Conformal blocks (i.e. chiral correlation functions) are central objects of chiral CFT. Given a VOA V and a compact Riemann surface C with marked points, one can define conformal blocks to be linear functionals on tensor products of V-modules satisfying certain (co)invariance properties related to V and C. For instance, the vertex operator of a VOA V, or more generally, an intertwining operator of V, is a conformal block associated to V and the genus 0 Riemann surface with 3 marked points. Taking contractions/q-traces is a main way of constructing higher genus conformal blocks from low genus ones, and it has been conjectured for a long time that the contractions always converge. In this talk, I will report recent work on a solution of this conjecture.

  • Speaker Thomas Gemünden, ETH Zürich
    • Title Non-abelian orbifold theory and holomorphic vertex operator algebras at higher central charge
    • Time 11/20/2020, Friday, 12:00 (Eastern Time)
    • Location Zoom link above
    • Abstract Holomorphic vertex operator algebras at central charges up to 24 have been almost fully classified and it appears that they can all be constructed as cyclic orbifolds of lattice vertex operator algebras. At the same time, very little is known about the situation at higher central charge. Intuition from physics tells us that higher central charge analogues of the moonshine vertex operator algebra may exist, but so far all attempts at their construction have failed. The goal of this work is to explore the set of holomorphic vertex operator algebras at higher central charge using non-abelian orbifold theory.

      I will begin the talk with a review of the orbifold theory of strongly rational vertex operator algebras. Then I will develop a theory of holomorphic extensions of metacyclic orbifolds as a generalisation of the cyclic theory.

      Finally, I will prove the existence of a holomorphic vertex operator algebra at central charge 72 that cannot be constructed as a cyclic orbifold of a lattice vertex operator algebra. If there is time I will discuss some of the challenges arising in trying to construct analogues of the moonshine module.

Some additional talks by members of this seminar

  • Speaker Yi-Zhi Huang, Rutgers University
    • Title Associative algebras and the representation theory of grading-restricted vertex algebras
    • Event Rocky Mountain Representation Theory Seminar
    • Time 11/5/2020, Thursday, 1:00 pm Mountain Time or 3:00 pm Eastern time
    • Location See the Zoom link in the web page of Rocky Mountain Representation Theory Seminar above
    • Abstract I will introduce an associative algebra A^{?}(V) constructed using infinite matrices with entries in a grading-restricted vertex algebra V. The Zhu algebra and its generalizations by Dong-Li-Mason are very special subalgebras of A^{?}(V). I will also introduce the new subalgebras A^{N}(V) of A^{?}(V), which can be viewed as obtained from finite matrices with entries in V. I will then discuss the relations between lower-bounded generalized V-modules and suitable modules for these associative algebras. This talk is based on the paper arXiv:2009.00262.

      pdf file of the slides of the talk.

  • Speaker Yi-Zhi Huang, Rutgers University
    • Title ?????????????????(Representation theory of vertex operator algebras and conformal field theory, in Chinese)
    • Event ?????????????????
    • Time 11/29/2020, Sunday, 8:30 am Beijing Time or 11/28/2020, Saturday, 7:30 pm Eastern time
    • Location See the Tecent meeting link in the web page above
    • Abstract ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

  • Speaker Yi-Zhi Huang, Rutgers University
    • Title Representation theory of vertex operator algebras and orbifold conformal field theory
    • Event Talks in mathematical physics, Department of Mathematics, ETH Zürich
    • Time 12/3/2020, Thursday, 3:15 pm Central European Time or 9:15 am Eastern time
    • Location See the Zoom link in the web page of Talks in mathematical physics above
    • Abstract In this talk, I will discuss a program to develop orbifold conformal field theory using the representation theory of vertex operator algebras. The construction and existence of twisted modules and the definition and basic properties of twisted intertwining operators will be reviewed briefly. The conjectural properties, including the associativity, commutativity and modular invariance of twisted intertwining operators, will be formulated explicitly. The main conjectures in orbifold conformal field theory will be stated precisely. Some thoughts on the further development of orbifold conformal field theory will be discussed.

      pdf file of the slides of the talk.