Lower bound on the four-point dynamical susceptibility: Direct experimental test on a granular packing

F. Lechenault , Olivier Dauchot (1) , G. Biroli (2) , J. P. Bouchaud (1, 3)

1 SPEC - UMR3680 - Service de physique de l'état condensé
2 SPhT - Service de Physique Théorique
3 Science and Finance, CFM

We track the motion of a horizontally vibrated amorphous assembly of bidisperse hard disks, for densities ranging across the jamming transition. We derive on very general grounds a bound on the dynamical susceptibility in terms of the response of the dynamics to a change in density. This generalizes a similar bound recently derived for equilibrium liquids. We find that in our experimental system the bound is tight and reproduces the non-monotonic behavior of the dynamical susceptibility both in time and density across the jamming transition. The underlying scaling behavior reveals an intimate connection between anomalous diffusion and dynamical heterogeneity.

Domaines: Matière Molle [cond-mat.soft]

F. Lechenault, Olivier Dauchot, G. Biroli, J. P. Bouchaud. Lower bound on the four-point dynamical susceptibility: Direct experimental test on a granular packing. 2007. ⟨hal-00200704⟩