Energy diffusion in hard-point systems L. Delfini, S. Denisov, S. Lepri, R. Livi, P. K. Mohanty and A. Politi Eur. Phys. J. Special Topics, 146 (2007) 21-35 Published online: 05 July 2007 DOI: 10.1140/epjst/e2007-00166-y