2 00 5 Moments of Wigner function and Renyi entropies at freeze - out

Relation between Renyi entropies and moments of the Wigner function, representing the quantum mechanical description of the M-particle semi-inclusive distribution at freeze-out, is investigated. It is shown that in the limit of infinite volume of the system, the classical and quantum descriptions are equivalent. Finite volume corrections are derived and shown to be small for systems encountered in rela-tivistic heavy ion collisions. 1 Introduction It is widely recognized that information on the entropy of the systems produced in high-energy collisions is very useful in understanding the physics of the process in question. This is particularly important for heavy ion collisions and search for quark-gluon plasma. It was suggested some time ago [1] that measurements of coincidences between the events observed in high-energy experiments may provide an estimate of the Renyi entropies [2] of the