Abstract

Critical indices $\ensuremath{\beta}$, $\ensuremath{\gamma}$ $\ensuremath{\delta}$, $\ensuremath{\nu}$, etc. are defined and calculated for self-organized critical phenomena. Scaling relations are derived and checked numerically. The order-parameter exponent $\ensuremath{\beta}$ describes the spontaneous current and the relaxation to the critical point. The power spectrum has "$\frac{1}{f}$" behavior with exponent $\ensuremath{\varphi}=\frac{\ensuremath{\gamma}}{\ensuremath{\nu}z}$, where $z$ is the dynamical critical exponent.