Rotational sandpile models: A finite size scaling study
Abstract Nontrivial critical behaviour is observed in equilibrium lattice statistical models under rotational constraint. Effect of rotational constraint on lattice statistical models at out of equilibrium situation is important to study. Critical properties of non-equilibrium steady state of sandpile models are studied under rotational constraint via finite size scaling (FSS) analysis. Not only FSS is found to be valid for a wide range of rotational sandpile models but also they are found to belong to the same universality class.
Universality in sandpile models.
A new classification of sandpile models into universality classes is presented. On the basis of extensive numerical simulations, in which we measure an extended set of exponents, the Manna two state model [S. S. Manna, J. Phys. A 24, L363 (1991)] is found to belong to a universality class of random neighbor models which is distinct from the universality class of the original model of Bak, Tang and Wiesenfeld [P. Bak, C. Tang and K. Wiensenfeld, Phys. Rev. Lett. 59, 381 (1987)]. Directed models are found to belong to a universality class which includes the directed model introduced and solved by Dhar
COMMENT: Statistics of spiral lattice site animals with loops
For spiral lattice site animals embedded in the square lattice the authors conjecture a relation θc = θ - αc where θc is the animal number exponent for animals with c loops, θ0 is the exponent for trees and α is a numerical constant of approximate value 1.62. This result is different from the relation θc= θ0 - c which holds true for both undirected and directed animals.