Math 555

Math 555

Selected Topics in Algebra

Nonlinear sigma-models and Riemannian geometry

Spring, 2013

MTh3 12:0 PM--1:20 PM HLL-423

Nonlinear sigma-models are a class of two-dimensional quantum field theories from which physicists have obtained many deep conjectures in topology and geometry. Unfortunately nonlinear sigma-models are still not constructed mathematically. In this course, I will cover the following topics:

  1. Nonlinear sigma-models from a mathematical point of view; conjectures obtained by physicists, including, in particular, those on Calabi-Yau manifolds and elliptic genera.

  2. The mathematical construction of linear sigma-models, that is, sigma-models with flat target spaces.

  3. My recent results in a program of constructing nonlinear sigma-models; Laplacians and sheaves of meromorphic open-string vertex algebras and modules on Riemannian manifolds.

  4. My recent results on Witten's Dirac-like operator on a loop space and their connection with Witten genus.

Prerequisites: Algebra and analysis at the level of first year graduate courses. Exposure to the theory of vertex operator algebras and Riemnnian geometry will be helpful but is not required.

Text: Some papers to be distributed in the classes, including, in particular:

  • E. Witten, Elliptic genera and quantum field theory, Comm. Math. Phys. 109 (1987), 525-536.

  • B. Greene, String Theory on Calabi-Yau Manifolds, hep-th/9702155.

  • Yi-Zhi Huang, Meromorphic open-string vertex algebras, arXiv:1204.1774.

  • Yi-Zhi Huang, Meromorphic open-string vertex algebras and Riemannian manifolds,arXiv:1205.2977.

  • Some other papers.