Generic slow relaxation in a stochastic sandpile

Simulations of a stochastic fixed-energy sandpile in one and two dimensions reveal slow relaxation of the order parameter, even far from the critical point. The decay of the activity is best described by a stretched-exponential form. The persistence probability (for a site not to have toppled up to time t), also exhibits stretched-exponential relaxation. The results suggest a connection between sandpile models and structural glasses.