“…Another quantity of interest in price dynamics is the return . Its statistical analysis is well known as distribution of returns: , where the long tail cumulative probabilities distribution of volatilities g obeys to an inverse cubic-law , where is the tail exponent [ 4 , 6 , 9 , 14 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”