Observing Non-Gaussian Sources in Heavy-Ion Reactions

We examine the possibility of extracting non-Gaussian sources from two-particle correlations in heavy-ion reactions. Non-Gaussian sources have been predicted in a variety of model calculations and may have been seen in various like-meson pair correlations. As a tool for this investigation, we have developed an improved imaging method that relies on a Basis spline expansion of the source functions with an improved implementation of constraints. We examine under what conditions this improved method can distinguish between Gaussian and non-Gaussian sources. Finally, we investigate pion, kaon, and proton sources from the p-Pb reaction at 450 GeV/nucleon and from the S-Pb reaction at 200 GeV/nucleon studied by the NA44 experiment. Both the pion and kaon sources from the S-Pb correlations seem to exhibit a Gaussian core with an extended, non-Gaussian halo. We also find evidence for a scaling of the source widths with particle mass in the sources from the p-Pb reaction.Comment: 16 pages, 15 figures, 5 tables, uses RevTex3.

Interferometry with Resonances and Flow in High-Energy Nuclear Collisions

The effects of resonances and flow on the correlation function for two identical particles are described assuming chaotic sources and classical propagation of particles. Expanding to second order in relative momenta, the source sizes can be calculated directly and understood as contributions from various fluctuations in the source. Specific calculations of source size radii are given assuming Bjorken longitudinal flow with additional transverse expansion. Results are compared to recent $\pi\pi$ and $KK$ correlation data from relativistic nuclear collisions with particular attention to the reduction in the $\pi\pi$ correlation function due to resonances and the decreasing source sizes with increasing transverse momenta of the particles.Comment: 8 pages including 2 figure