Net Proton Flow and Nuclear Transparency Effects at RHIC : A Multiple Fireball Model approach

TL;DR

This paper applies a multiple fireball model to describe proton, antiproton, and kaon rapidity spectra at RHIC, emphasizing the dominance of resonance decay products and the use of a single temperature parameter across fireballs.

Contribution

It extends a recent model to successfully fit a wide range of particle spectra at RHIC with a unified temperature and detailed resonance decay contributions.

Findings

Model accurately reproduces proton and antiproton rapidity spectra.

Resonance decay products dominate over thermal protons and antiprotons.

A single temperature parameter suffices for all fireballs.

Abstract

Recently Beccattini and Cleymamns have proposed a model to understand the p-pbar data obtained at RHIC and SPS. We have shown that this model has a much greater applicability and can very well be used to describe the rapidity spectra of protons and antiprotons separately measured at the highest energy of Relativistic Heavy Ion Collider i.e., 200 GeV/A by BRAHMS Collaboration. We have also determined that the contribution of the decay products of the heavier resonances like delta, lambda etc. actually dominate over the protons (antiprotons) of pure thermal origin. We have also imposed the criteria of exact strangeness conservation in each fireball separately. It is shown that it is possible to explain not only the p-pbar data but the complete set of data viz. the rapidity distributions of protons, antiprotons and the ratio pbar/p simultaneously quite well with a single set of model parameters which includes a single value of the temperature parameter T chosen for all the fireballs. We have also fitted the Kaon rapidity spectra obtained by BRAHMS collaboration in the same experiment. This is unlike the previous analyses wherein a varying temperature has been assumed for the fireballs formed along the rapidity axis. The chemical potentials are however assumed to be dependent on the fireball rapidity yfb.