title: Jamming as a critical phenomenon: a field theory of zero-temperature grain packings.
abstract: A field theory of frictionless grain packings in two dimensions is shown to exhibit a zero-temperature critical point at a nonzero value of the packing fraction. The zero-temperature constraint of force balance plays a crucial role in determining the nature of the transition. Two order parameters, <z>, the deviation of the average number of contacts from the isostatic value, and <phi>, the average magnitude of the force per contact, characterize the transition from the jammed (high packing fraction) to the unjammed (low packing fraction state). The critical point has a mixed character with the order parameters showing a jump discontinuity but with fluctuations of the contact force diverging. At the critical point, the distribution of phi shows the characteristic plateau observed in static granular piles. The theory makes falsifiable predictions about the spatial fluctuations of the contact forces.
authors.affiliation: Martin Fisher School of Physics, Brandeis University, Mail Stop 057, Waltham, Massachusetts 02454-9110, USA.
authors.forename: Silke
authors.initials: S
authors.lastname: Henkes
authors.forename: Bulbul
authors.initials: B
authors.lastname: Chakraborty
mesh_terms: D000465:Algorithms; D019277:Entropy; D015233:Models, Statistical; D055585:Physical Phenomena; D010825:Physics; D011208:Powders; D013696:Temperature
chemical_list: D011208:Powders