The gradually truncated Lévy flight for systems with power-law distributions

Power-law distributions have been observed in various economical and physical systems. Lévy flights have infinite variance which discourage a physical approach. We introduce a class of stochastic processes, the “gradually truncated Lévy flight” in which large steps of a Lévy flight are gradually eliminated. It has finite variance and the system can be analyzed in a closed form. We applied the present method to explain the distribution of a particular economical index. The present method can be applied to describe time series in a variety of fields, i.e. turbulent flow, anomalous diffusion, polymers, etc.