Universality classes in the random-storage sandpile model

The avalanche statistics in a stochastic sandpile model where toppling takes place with a probability p is investigated. The limiting case p=1 corresponds to the Bak-Tang-Wiesenfeld (BTW) model with deterministic toppling rule. Based on the moment analysis of the distribution of avalanche sizes we conclude that for 0<p<p_c the model belongs to the DP universality class while for p_c<p<1 it belongs to the BTW universality class, where p_c is identified with the critical probability for directed percolation in the corresponding lattice.