RENORMALIZATION PROCEDURE FOR DIRECTED SELF-ORGANIZED CRITICAL MODELS

Directed models of self-organized criticality are studied in the frame work of a real-space renormalization group of a different type. The id entification of a suitable phase space in which to define the renormal ization transformation and the coupling with the stationarity conditio n enables us to clarify the nature of the critical state. The renormal ization equations are found to have an attractive fixed point, as expe cted from the self-critical nature of the model. The values of the cri tical exponents obtained by this procedure are in excellent agreement with exact results.