Speaker: 韩飞（新加坡国立大学）

Time: 14:00-15:00, May. 31

Online: 腾讯会议：793-692-902

Title: Modular invariants twisted by gerbe modules and applications

Abstract:

Projective vector bundles (or more generally gerbe modules in the non-torsion flux case) are generalizations of vector bundles in the presence of a gerbe on manifolds. Given a projective vector bundle or gerbe module, we will first show how to use it to twist the Witten genus to get modular invariants. Then we will give two applications around this construction: (1) the first application is in the differential operators on manifolds: given any pseudodifferential operator, we will construct modular invariants generalizing the Witten genus, which corresponds to the Dirac operator; (2) the second application is in M-theory: we will construct the graded Hori map in the topological T-duality and show that it sends Jacobi forms to Jacobi forms. The talk is based on the joint works with Mathai.