Effective potentials of dissipative hard spheres in granular matter R. A. Bordallo-Favela, A. Ramírez-Saíto, C. A. Pacheco-Molina, J. A. Perera-Burgos, Y. Nahmad-Molinari and G. Pérez Eur. Phys. J. E, 28 4 (2009) 395-400 Published online: 21 March 2009 DOI: 10.1140/epje/i2008-10432-2