SEMINAIRE MERCREDI 3 NOVEMBRE 2004 14 heures Salle Séminaire 5 Centre de Physique Théorique Marseille-Luminy Antonio Ponno CPT Title: Energy cascade in oscillator chains: The FPU problem Abstract: An analytical study of the classical Fermi-Pasta-Ulam problem is presented. The core of method is based on the approximation of the FPU dynamics by means of suitable partial differential equations which constitute the resonant normal form in the problem at hand. Through dimensional-singularity analysis we give estimates of some relevant quantities characterizing the energy spectrum of Fourier modes in the state of meta-equilibrium. The result presented are part of a work in progress done in collaboration with Dario Bambusi (Universita' di Milano).