title: Correlations and critical behavior of the q model.
abstract: The q model is a random walk model used to describe the flow of stress in a stationary granular medium. Here we derive the exact horizontal and vertical correlation functions for the q model in two dimensions. We show that close to a critical point identified in earlier work these correlation functions have a universal scaling form reminiscent of thermodynamic critical phenomena. We determine the form of the universal scaling function and the associated critical exponents ν and z.
authors.affiliation: Department of Physics, University of Wisconsin Parkside, Kenosha, Wisconsin 53144, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: St John
authors.forename: Harsh
authors.initials: H
authors.lastname: Mathur