title: Particle-density fluctuations and universality in the conserved stochastic sandpile.
abstract: We examine fluctuations in particle density in the restricted-height, conserved stochastic sandpile (CSS). In this and related models, the global particle density is a temperaturelike control parameter. Thus local fluctuations in this density correspond to disorder; if this disorder is a relevant perturbation of directed percolation (DP), then the CSS should exhibit non-DP critical behavior. We analyze the scaling of the variance Vℓ of the number of particles in regions of ℓd sites in extensive simulations of the quasistationary state in one and two dimensions. Our results, combined with a Harris-like argument for the relevance of particle-density fluctuations, strongly suggest that conserved stochastic sandpiles belong to a universality class distinct from that of DP.
authors.affiliation: Departamento de Física, ICEx, Universidade Federal de Minas Gerais, Caixa Postal 702, 30161-970 Belo Horizonte, Minas Gerais, Brazil.|National Institute of Science and Technology of Complex Systems, Caixa Postal 702, 30161-970 Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Ronald
authors.initials: R
authors.lastname: Dickman
authors.affiliation: Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, Campus Universitário, 59078-970 Natal, Rio Grande do Norte, Brazil.
authors.forename: S D
authors.initials: SD
authors.lastname: da Cunha