Systematics of Soft Particle Production at RHIC: Lessons from PHOBOS

TL;DR

This paper analyzes extensive data from the PHOBOS experiment on particle production in heavy ion collisions at RHIC, revealing simple scaling behaviors and discussing implications for future LHC measurements.

Contribution

It provides a comprehensive systematic study of soft particle production across energies, system sizes, and kinematic ranges, highlighting simple factorization properties and new analysis techniques.

Findings

Particle yields scale with energy and system size

Identified particle spectra show simple factorization

New correlations and rare event searches expand understanding

Abstract

The PHOBOS experiment has measured the properties of particle production in heavy ion collisions between sqrt(s_NN) of 20 and 200 GeV. The dependencies of charged particle yield on energy, system size, and both longitudinal and transverse momentum have been determined over close to the full kinematic range. Identified charged particles emitted near mid-rapidity have been studied over about 2 orders of magnitude in transverse momentum. This broad data set was found to be characterized by a small number of simple scalings which factorize to a surprising degree. This study has recently been extended by the addition of new data for Cu+Cu as well as new analyses of Au+Au data, including more peripheral collisions. In addition, the exploration of global properties has been expanded with the use of new techniques, including two-particle correlations, more sensitive searches for rare events, and more detailed studies of particles emitted at very forward rapidity. The characteristics of particle production which are revealed by this extensive data set will be described along with the implications for future data from the LHC.