Phi-measure of pions in high energy heavy-ion collisions

Event-by-Event fluctuations for high energy heavy-ion collisions are investigated. The $\Phi$-measures are calculated for pions. It is found that multiparticle symmetrization correlation has great influence on the value of $\Phi$ if the phase space density is high. Previous derivation of $\Phi$-measure has neglected multiparticle quantum correlation. So the explanation of $\Phi$-measure as a measure of dynamical correlation is reasonable only when multiparticles quantum correlation effects are smaller. We argue that the $\Phi$-measure might be applicable at the SPS energy where the pion phase space density is much less than one.