Aktuelles

Dienstag, 21.04.2026: Piecewise quasipolynomiality of double tropical Welschinger invariants for toric surfaces

Vincenzo Reda (Trinity College, Dublin)

Relative tropical Welschinger invariants of real toric surfaces, introduced by Itenberg, Kharlamov, and Shustin, count totally real tropical curves subject to point and tangency conditions and discrete data. Double tropical Welschinger invariants of toric surfaces are the relative invariants for which tangency conditions are imposed along two parallel toric divisors. In this setting, the enumeration of tropical curves is replaced by the enumeration of real floor diagrams. In this talk, I will outline the proof that these invariants are piecewise quasipolynomial in the tangency orders and in the parameters of the surface, using results from weighted Ehrhart theory. Finally, I will present an analogous result for counting real floor diagrams with non-empty imaginary part.

Uhrzeit:	10:00 - 11:00
Ort:	C4H33
Gruppe:	Oberseminar kombinatorische algebraische Geometrie
Einladender:	Daniele Agostini, Hannah Markwig

Dienstag, 21.04.2026: Quantum ergodicity in the Benjamini-Schramm limit for locally symmetric spaces

Carsten Peterson (Sorbonne Université)

Originally, quantum ergodicity referred to the equidistribution of Laplacian eigenfunctions with large eigenvalue on manifolds with ergodic geodesic flow, such as hyperbolic surfaces. The pioneering work of Anantharaman-Le Masson '15 brought such ideas to the setting of (regular) graphs. However, here one takes a "large spatial limit" rather than a large eigenvalue limit. Quantum ergodicity in the Benjamini-Schramm limit, as it has come to be known, was later also studied for hyperbolic surfaces and other rank one locally symmetric spaces. In joint work with Farrell Brumley, Simon Marshall, and Jasmin Matz we prove analogous results for arbitrary higher rank compact locally symmetric spaces (with a few exceptions).

Uhrzeit:	14:15
Ort:	C9A03
Gruppe:	Oberseminar Analysis un Zahlentheorie
Einladender:	Deitmar

Donnerstag, 23.04.2026: Short presentations by research group members

Tejal Bhattarai, Till Falkenhagen, Luca Koch, Colin Kühner, Andoni Royo Abrego, Saradha Senthil Velu, Salvatore Vultaggio

Each of the speakers will give a 5-10min informal presentation of the research questions they are currently pursuing in their Bachelor, Master, or PhD thesis. Students interested in the research of the group are particularly welcome to join!

Uhrzeit:	14:00 - 15:30
Ort:	C4H33
Gruppe:	Oberseminar GADR
Einladender:	Carla Cederbaum, Gerhard Huisken

Donnerstag, 23.04.2026: Slow propagation velocities in quantum many-body dynamics

Dr. Jingxuan Zhang (Tsinghua University, China)

We study the localization bounds for quantum many-body systems at positive spatial density in disordered media. Specifically, we consider dynamics of interacting bosons in the mean-field regime, subjected to a disordered potential which is either random or quasi-periodic. We prove that starting from a factorized and spatially localized initial wave function, the corresponding time-evolution propagates with a small velocity due to the disorder. This provides an example of a disordered quantum many-body system with provably slow transport behavior in any spatial dimension. The main technical novelty in the proof is an interaction picture analysis relative to the localization bounds of the associated one-body dynamics.

Uhrzeit:	14:30
Ort:	C3N14
Gruppe:	Oberseminar Mathematical Physics
Einladender:	Keppeler, Lemm, Pickl, Teufel, Tumulka

Donnerstag, 23.04.2026: Markovization in Classical Statistical Mechanics

Arnulf Kung (Tübingen)

It is the key problem of statistical mechanics to explain the macroscopic thermodynamic behaviour of physical systems in terms of the underlying, fundamental microscopic laws. Though the H-Theorem of Boltzmann provides such a derivation, it is restricted to a special system, the dilute gas. Several authors, such as Nico van Kampen and Oliver Penrose, have presented corresponding results for a broader class of systems, whose derivations are based on the Markov property of a system at the macro level. In this talk, we will critically examine this approach. We will start with analysing additional dynamical assumptions that have been suggested to assure a system behaves Markovian. Since it is very reasonable that realistic systems do not satisfy these assumptions exactly, we will turn to the question whether, if this is indeed not the case, they can at least still be 'nearly Markovian' over arbitrarily long scales of time. Furthermore, we will investigate whether slightly non-Markovian processes can be approximated arbitrarily well by ones with the full Markov property.

Uhrzeit:	16:00
Ort:	C3N14
Gruppe:	Oberseminar Mathematical Physics
Einladender:	Keppeler, Lemm, Pickl, Teufel, Tumulka