# Agenda

# Wednesday 10 November 2021

### Étude semiclassique de l’interaction d’Yukawa et ses champs asymptotiques

#### Zied Amarri, Université de Rennes

### Quantum graphs with uncommon vertex couplings

#### Pavel Exner, Université de Prague

The main topic of this talk are quantum graphs with the vertex coupling violating the time-reversal invariance. We explain why such systems can be useful in physics and as a case study we analyze a simple example in which the asymmetry is maximal at a fixed energy. This leads to an interesting property, namely that high-energy scattering depends crucially on the vertex parity; we will demonstrate implications of this fact for spectral and transport properties in several classes of graphs, both finite and infinite periodic ones. We will also discuss other time-asymmetric graphs and identify a class of such couplings which exhibits a nontrivial PT-symmetry despite being self-adjoint. The results come from a common work with Marzieh Baradaran, JirI Lipovsky , and Milos Tater.