The seminar takes place on Tuesdays, usually from 16:00 to 17:00 CEST (UTC+2, time zone of Amsterdam, Berlin,
Rome, Stockholm, Vienna) via Zoom . The meetings start 15 minutes before the talk with a short coffee break.
The password is the first Fourier coefficient of the modular $j$-function (as digits).
The videos of some of the past talks are available on our youtube channel. In September 2025, we organized the "International Workshop on Automorphic Forms" (IWoAF) at SwissMap research station. Some of the talks are recorded and available from the link below.
If you wish to receive emails with news about the seminar and reminders for talks, please just write to one of the organizers about joining our mailing list.
16.06.2026 -- 16:00-17:00 (CEST, UTC+2)
Trajan Hammonds (Aarhus) A Geometric Approach to Ki's $L^4$ Norm Bound
The behavior of $L^p$ norms of automorphic forms is a central topic in analytic number theory. In 2023, Haseo Ki proved the Iwaniec-Sarnak conjecture for $L^4$ norms for Hecke-Maass cusp forms, long thought to be out of reach. In this talk, I will present joint work with Anshul Adve, along with work of Paul Nelson, providing a new proof of Haseo Ki's optimal $L^4$ norm bound. The key novelty is avoiding a hands-on analysis of Bessel function asymptotics, at least in the critical range. Instead we are able to recast the essential estimates into a simple problem in incidence geometry and solve it.
23.06.2026 -- 16:00-17:00 (CEST, UTC+2)
Noam Kimmel (MPIM Bonn) Zeros of Poincaré series
We explore the zeros of certain Poincaré series P(k,m) of weight k and index m for the full modular group. These are distinguished modular forms, which have played a key role in the analytic theory of modular forms. We study the zeros of P(k,m) when the weight k tends to infinity. The case where the index m is constant was considered by Rankin who showed that in this case almost all of the zeros lie on the unit arc |z|=1. In this talk we will explore the location of the zeros when the index m grows with the weight k, finding a range of different limit laws. Along the way, we also establish a version of Quantum Unique Ergodicity for some ranges.
30.06.2026 -- 10:00-11:00 (CEST, UTC+2)
Haocheng Fan (BICMR - Peking University) On an algebro-geometric approach to the automatic convergence theorem for Shimura varieties
In the first part of this talk, I will provide an upper bound for the coherent cohomological dimension of the Siegel modular variety, and then show that the boundary of the compactified Siegel modular variety satisfies the Grothendieck–Lefschetz condition, which implies the automatic convergence theorem in this case. In the second part, I will introduce a work in progress, joint with Peihang Wu and Jiacheng Xia, to generalize this approach to general Shimura varieties by assuming an algebraicity result on the space of symmetric formal Fourier-Jacobi series.
07.07.2026 -- 16:00-17:00 (CEST, UTC+2)
Ryan Chen (Princeton) TBA
