Realistic Expanding Source Model for Relativistic Heavy-Ion Collisions

Abstract

We introduce a new realistic expanding source model for invariant one-particle multiplicity distributions and two-particle correlations in nearly central relativistic heavy-ion collisions that contains nine adjustable parameters, which are necessary and sufficient to properly characterize the gross properties of the source during its freezeout from a hydrodynamical fluid into a collection of noninteracting, free-streaming hadrons. These nine physically relevant parameters fall into three categories of three parameters each, with the first category corresponding to the source's longitudinal motion, the second category corresponding to its transverse motion, and the third category corresponding to its intrinsic properties. As an initial application, we apply our model to the analysis of invariant pi^+, pi^-, K^+, and K^- one-particle multiplicity distributions and pi^+ and K^+ two-particle correlations for nearly central Si + Au collisions at p_lab/A = 14.6 GeV/c. In a minimization with 1416 data points, the resulting chi-square is 1484.6, which corresponds to an acceptable chi-square per degree of freedom of 1.055. We list the values of the nine parameters determined this way plus several additional calculated freezeout quantities of physical interest, along with their uncertainties at 99% confidence limits.