Prof. Thomas Richthammer (Univ. Hildesheim) Title: The variance of particle positions in the hard disk model When: Martedi' 12 Maggio 2015 ORE 15:00 Where: Dipartimento di Matematica e Fisica Universita' degli Studi Roma Tre AULA 311 (SEMINARI) Largo San L. Murialdo,1 Abstract: The hard disk model describes random configurations of disks in the plane, interacting only via hard core exclusion. It is believed that the model exhibits a weak form of crystallization for large activity (i.e. high particle density). In spite of its simplicity, there are only very few rigorous results on the hard disk model. I will present a very recent result which can be interpreted as a lower bound on the variance of particle positions in terms of the size of the system. The result is obtained via a certain tansformation on particle configurations. It builds on an earlier result concerning the absence of positional order.