Dynamical behavior of excited hadronic matter

Abstract

Hadronic multiplicity moments referred to phase space rapidity bins of variable size give important information on the underlying correlations in the multiparticle production mechanisms for hadronic and nuclear collisions. Ordinary factorial moments given by integrals of density correlations contain background contributions that can be removed by expanding in cumulants. This expansion has a simple exact form even in the absence of rapidity translation invariance when the bin averages are done locally. We have used these identities to extract second through fifth order correlation from various reactions. The behavior of the second bin-averaged factorial moment is and must be in agreement with the identity relating it to the empirical two-particle correlation function. Higher order moments have been successfully explained by the linked pair approximation that expresses higher cumulant correlations as products of the two particle correlation function. Remarkably, the undetermined coefficients in this approach turn out to closely approximate those needed to give the negative binomial distribution, the latter successfully describing hadron counts in rapidity bins of arbitrary size. At collider energy we can extract higher order cumulant correlations, which agree well with the linked pair approximation that we introduced last year. Quantitative analysis of theses and other data show saturationmore » of the moments for small bin size rather than scaling intermittent'' behavior.« less