Oberseminar WiSe 25/26
Die Vorträge finden jeweils donnerstags um 16:45 Uhr im Raum WSC-N-U-3.05 (im Mathematikgebäude ) statt.
Der Tee findet ab 16:15 in Raum O-3.46 statt.
Alle Interessenten sind herzlich eingeladen!
The seminar takes place on Thursday, starting at 4:45pm. The duration of each talk is about 60 minutes. Before the talk, at 4:15pm, there is tea in room O-3.46.
Everybody who’s interested is welcome to join.
Directions from the train station.
| 16.10.2025 | Jaya Iyer (Chennai) | Period index questions for hyperelliptic curves |
| 23.10.2025 | Job Kuit (Paderborn) | On norms on Harish-Chandra modules |
| 13.11.2025 | Yu LUO (Univ. of Wisconsin-Madison) | A new proof of the arithmetic Siegel—Weil formula |
| 20.11.2025 | Enya Hsiao (MPI – MIS) | BAA-branes from Higher Teichmüller Theory |
| 27.11.2025 | Karin Baur (Univ. Bochum) | t.b.a. |
| 04.12.2025 | Matilde Maccan (Bochum) | t.b.a. |
| 11.12.2025 | Rin Ray (Münster) | t.b.a. |
| 18.12.2025 | Christian Maire, (Univ. Marie et Louis Pasteur) | t.b.a. |
| 08.01.2026 | Louis Dailly (Toulouse) | t.b.a. |
| 15.01.2026 | Christian Dahlhausen (Heidelberg) | t.b.a. |
| 22.01.2026 | Timo Richarz (TU Darmstadt) | t.b.a. |
| 29.01.2026 | Mihai Pavel (Bukarest) | Projectivity of moduli spaces of sheaves without GIT |
| 05.02.2026 | Britta Späth (Wuppertal) | t.b.a. |
Abstracts
Jaya Iyer: Period index questions for hyperelliptic curves
We will discuss period-index question for Brauer group of fields. In particular we will consider function fields of hyperelliptic curves over number fields. We show that period equals index for 2-torsion Brauer elements under, local triviality conditions.
Job Kuit: On norms on Harish-Chandra modules
A Harish-Chandra module is the algebraic “skeleton” of an irreducible continuous representation of a real reductive group. For a given Harish-Chandra module there are typically many continuous representations that correspond to it. In this talk we will explore to what extend continuous representations (in particular on Banach spaces) with the same Harish-Chandra module may differ from each other, and discuss some relations to automorphic forms. (This is joint work with Joseph Bernstein, Pritam Ganguly, Bernhard Krötz and Eitan Sayag.)
Yu Luo: A new proof of the arithmetic Siegel—Weil formula
The arithmetic Siegel-Weil formula establishes a profound connection between intersection numbers in Shimura varieties and the Fourier coefficients of central derivatives of Eisenstein series. This result was proven by C. Li and W. Zhang in 2021 using local methods. In this talk, I will present a new proof of the formula that uses the local-global compatibility and the modularity of generating series of special divisors.
Enya Hsiao: BAA-branes from Higher Teichmüller Theory
In recent years, a general Cayley correspondence has been proposed by Bradlow et al. motivated by higher Teichmüller theory. To each magical sl2-triple, they constructed an open, closed and injective map called the Cayley map between Higgs bundle moduli spaces, whose image is a union of higher Teichmüller components. In this talk, I will explain how we used the notion of Gaiotto’s Lagrangian from derived symplectic geometry to extend Cayley map to a morphism of BAA-branes on the level of Higgs stacks, and our conjecture of their BBB-brane duals. This is joint work with Eric Chen and Mengxue Yang.