Centrality dependence of charged-particle pseudorapidity distributions from d+Au collisions at sqrt(s_{NN})=200 GeV

TL;DR

Charged-particle pseudorapidity densities are presented for the d + Au reaction at sqrt[s(NN)] = 200 GeV and the data do not support predictions based on strong-coupling, semiclassical QCD.

Abstract

Charged-particle pseudorapidity densities are presented for the d+Au reaction at sqrt{s_{NN}}=200 GeV with -4.2 <= eta <= 4.2$. The results, from the BRAHMS experiment at RHIC, are shown for minimum-bias events and 0-30%, 30-60%, and 60-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semi-classical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt{s_{NN}}=19.4 GeV.

Figures (3)

• Figure 1: SiMA and TMA averaged multiplicity distribution normalized to the 1% centrality level. Lines show efficiency corrected limits for indicated centralities. The insert shows the correlation between the SiMA and TMA multiplicities.
• Figure 2: a) and b) Charged-particle pseudorapidity densities for indicated centrality ranges. c) Multiplicity ratios R$^{0-30}$ (squares) and R$^{30-60}$ (triangles), as discussed in the text. Statistical uncertainties are indicated by vertical lines or are smaller than the symbols. Detached horizontal brackets indicate the total (statistical and systematic) uncertainties. The solid, dashed and dotted curves in a) and b) are the results of the HIJING, AMPT and Saturation models, respectively. The curves in c) show the HIJING results for R$^{0-30}$ (solid) and R$^{30-60}$ (dashed), with the arrows indicating the values expected for Au- and d-participant, only, scaling. In all panels, the connected open circles (asterisks) correspond to unrestricted HIJING calculations with centrality classes based on multiplicity (impact paramter), as discussed in the text.
• Figure 3: Comparison of central $\sqrt{s_{NN}}=200\rm~GeV$ results(solid squares) with NA35 data (open squares) at $\sqrt{s_{NN}}=19.4\rm~GeV$ in a) the nucleon-nucleon center-of-mass system, b) the Au rest frame, c) the deuteron rest frame. The solid curve is based on data for Au+Au 0-30% central events at $\sqrt{s_{NN}}=200\rm~GeV$bearden02. $N_{part}$ scaling is applied as indicated in panel b).