International Seminar on Automorphic Forms

Zhiyuan Li (Fudan university)

Theta series and tautological cycles on orthogonal Shimura varieties

In this talk, I will explore the fascinating interplay between lattice theory and vector- valued modular forms via theta series, presenting an elegant connection that bridges these areas. I will discuss its applications in the study of cycle theory on orthogonal Shimura varieties. One of our findings reveal that the Picard group of the Baily-Borel compactification of a broad class of Shimura varieties is isomorphic to ℤ. I will also explain the geometric motivation of this project. Most results are joint work with Huang, Müller and Ye.

https://tu-darmstadt.zoom.us/j/68048280736

The password is the first Fourier coefficient of the modular j-function (as digits)