Glassy systems exhibit peculiar macroscopic features such as aging, rejuvenation and memory effects. Our present understanding of the underlying mechanism behind these striking features remains largely speculative because of our lack of knowledge on the processes taking place at mesoscopic scales. In this talk we discuss results of our recent theoretical studies in mean field spin-glass model about static responses to external perturbations in large but finite systems. We show that mesoscopic magnetization grows in a step-wise manner reflecting the rugged energy landscape at mesoscopic scales. Somewhat unexpectedly, the problem of such step-wise responses can be mapped precisely to a class of problems of shocks in turbulent flows. Finally, we discuss possible experiments and simulations to look for the shocks in glassy systems. Ref.: Step-wise responses in mesoscopic glassy systems: a mean field approach, Hajime Yoshino and Tommaso Rizzo, Phys. Rev. B 77, 104429 (2008). PS 1) Un caf’e sera servi à 11h PS 2) Hajime Yoshino intervient dans le cadre de son invitation par le Triangle de la Physique pour une s’erie de voyages au cours de cette ann’ee
Osaka University