Contacts Dynamics Reveals Widom Lines for Jamming

Abstract

We experimentally study the vicinity of the Jamming transition by investigating the statics and the dynamics of the contact network of an horizontally shaken bi-disperse packing of photo-elastic discs. Compressing the packing very slowly, while maintaining a mechanical excitation, yields a granular glass, namely a frozen structure of vibrating grains. In this glass phase, we observe a remarkable dynamics of the contact network, which exhibits strong dynamical heterogeneities. Such heterogeneities are maximum at a packing fraction ${\varphi }^{\ast }$, \emph{distinct} and smaller than the jamming packing fraction ${\varphi }_J$, which is indicated by the abrupt variation of the average number of contact per particle. We demonstrate that the two cross-overs, one for the maximum dynamical heterogeneity, and the other for static jamming, converge at point J in the zero mechanical excitation limit, a behavior reminiscent of the Widom lines in the supercritical phase of a second order critical point. Our findings are discussed in the light of recent numerical and theoretical studies of thermal soft spheres.

5 pages, 5 figures, to appear in EPL

References in corpus (3)

• The Jamming Transition in Granular Systems
• A microscopic mean-field theory of the jamming transition
• Critical scaling of jammed system after quench of temperature

Cited by in corpus (9)

• Dynamic criticality at the jamming transition
• Experimental evidences of the Gardner phase in a granular glass
• Theory of the Jamming Transition at Finite Temperature
• Shear modulus and Dilatancy Softening in Granular Packings above Jamming
• Local rheological measurements in the granular flow around an intruder
• Rheology of Weakly Vibrated Granular Media
• The Jamming point street-lamp in the world of granular media
• The glass transition in molecules, colloids and grains: universality and specificity
• Inferring the particle-wise dynamics of amorphous solids from the local structure at the jamming point