title: Robustness of scale invariance in models with self-organized criticality.
abstract: A random-neighbor extremal stick-slip model is introduced. In the thermodynamic limit, the distribution of states has a simple analytical form and the mean avalanche size, as a function of the coupling parameter, is exactly calculable. The system is critical only at a special point J(c) in coupling parameter space. However, the critical region around this point, where approximate scale invariance holds, is very large, suggesting a mechanism for explaining the ubiquity of power laws in nature.
authors.affiliation: Departamento de Física e Matemática, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, CEP 14040-901, Ribeirão Preto, SP, Brazil. osame@dfm.ffclrp.usp.br
authors.forename: O
authors.initials: O
authors.lastname: Kinouchi
authors.forename: C P
authors.initials: CP
authors.lastname: Prado