Multiscaling at Point J: jamming is a critical phenomenon

Area of Science:

• Physics
• Materials Science
• Statistical Mechanics

Background:

• The jamming transition describes the transition of granular materials from a flowing to a rigid state.
• Understanding this transition is crucial for predicting material behavior under stress.
• The jamming phase diagram provides a framework for studying these transitions under various conditions.

Purpose of the Study:

• To investigate the jamming transition at zero temperature (T=0) as a function of increasing packing density.
• To identify the order of the phase transition at "Point J" of the jamming phase diagram.
• To explore the nature of velocity fluctuations near the critical jamming density.

Main Methods:

• Analysis of a disordered two-dimensional assembly of disks.
• Measurement of the total number of moving disks.
• Quantification of the transverse length of the moving region.

Main Results:

• Observed a power-law divergence in the number of moving disks and transverse moving region length as packing density increased.
• Found evidence supporting a second-order phase transition at the critical jamming density.
• Detected multiscaling behavior in velocity fluctuations, suggesting the presence of long tails.

Conclusions:

• The T=0 jamming transition driven by packing density is a second-order phase transition.
• Multiscaling behavior highlights the significance of long-tailed velocity fluctuations near jamming.
• These findings contribute to a deeper understanding of the physics of jamming in disordered systems.