Centrality, system size and energy dependences of charged-particle pseudo-rapidity distribution

TL;DR

This study models charged-particle pseudorapidity distributions in heavy-ion collisions across various energies and systems, revealing the roles of leading particles, collision centrality, and system size, and predicting outcomes at LHC energies.

Contribution

It introduces a systematic analysis using the three-fireball quark combination model to understand pseudorapidity distributions and their dependencies in heavy-ion collisions.

Findings

Leading particle contribution increases with decreasing centrality and energy.

Number of leading particles is independent of collision energy but depends on nucleon participants.

Distributions are nearly identical for Cu+Cu and Au+Au collisions with same N_part at the same energy.

Abstract

Utilizing the three-fireball picture within the quark combination model, we study systematically the charged particle pseudorapidity distributions in both Au+Au and Cu+Cu collision systems as a function of collision centrality and energy, $\sqrt{s_{NN}}=$ 19.6, 62.4, 130 and 200 GeV, in full pseudorapidity range. We find that: (i)the contribution from leading particles to $dN_{ch}/d\eta$ distributions increases with the decrease of the collision centrality and energy respectively; (ii)the number of the leading particles is almost independent of the collision energy, but it does depend on the nucleon participants $N_{part}$; (iii)if Cu+Cu and Au+Au collisions at the same collision energy are selected to have the same $N_{part}$, the resulting of charged particle $dN/d\eta$ distributions are nearly identical, both in the mid-rapidity particle density and the width of the distribution. This is true for both 62.4 GeV and 200 GeV data. (iv)the limiting fragmentation phenomenon is reproduced. (iiv) we predict the total multiplicity and pseudorapidity distribution for the charged particles in Pb+Pb collisions at $\sqrt{s_{NN}}= 5.5$ TeV. Finally, we give a qualitative analysis of the $N_{ch}/<N_{part}/2>$ and $dN_{ch}/d\eta/<N_{part}/2>|_{\eta\approx0}$ as function of $\sqrt{s_{NN}}$ and $N_{part}$ from RHIC to LHC.