Higher Siegel-Weil formulas over function fields

Seminar: 
Geometry, Symmetry and Physics
Event time: 
Monday, March 8, 2021 - 4:30pm
Location: 
https://yale.zoom.us/j/92811265790 (Password is the same as last semester)
Speaker: 
Tony Feng
Speaker affiliation: 
IAS and MIT
Event description: 

The Siegel-Weil formula relates the integral of a theta function along a classical group H to a special value of a Siegel-Eisenstein series on another group G. Kudla proposed an "arithmetic analogue" of the Siegel-Weil formula, relating intersection numbers of special cycles on Shimura varieties for H to the first derivative at a special value of a Siegel-Eisenstein series on G. We study a function field analogue of this problem in joint work with Zhiwei Yun and Wei Zhang. We define special cycles on moduli stacks of unitary shtukas, construct associated virtual fundamental classes, and relate their degrees to the derivatives to *all* orders of Siegel-Eisenstein series. The results can be seen as “higher derivative” analogues of the Kudla-Rapoport Conjecture. Themes of geometric representation theory play an important role; in particular, a key to the proof is a categorification of local density formulas for Fourier coefficients of Eisenstein series, and a parallel categorification of the degrees of virtual fundamental classes of special cycles, in terms of a global variant of Springer theory.