Moment analysis of different stochastic directed sandpile model

We present large scale simulations of the non-Abelian stochastic directed sandpile model [Phys. Rev. Lett. 88 (2002) 054302] in two dimensions. We use moment analysis to evaluate critical exponents of the avalanches and finite size scaling method to consistently test the obtained results. In contrast to recently performed investigations, we find the values of the critical exponents of the non-Abelian stochastic directed model and the corresponding Abelian stochastic directed model [Phys. Rev. E 62 (2000) 5347] have different critical exponents, which indicate that they belong to different universality classes for the avalanches. The physical origin of the different critical behavior should be ascribed to the presence of the different avalanche structure in two models. In order to validate the accuracy of the moment analysis, we also use moment analysis to evaluate critical exponents of the Abelian stochastic directed model. We find the numerical values are consistent completely with the exact solution.