Spectra and nuclear modification factor of charged hadrons produced in lead-lead collisions at sqrt(s_NN)=2.76TeV with the ATLAS detector at the LHC

TL;DR

This paper reports on measurements of charged hadron spectra in lead-lead collisions at 2.76 TeV using the ATLAS detector, revealing significant suppression at certain transverse momenta indicative of hot dense matter effects.

Contribution

It provides detailed spectra and nuclear modification factors across centrality and pT ranges, enhancing understanding of energy loss in quark-gluon plasma.

Findings

Suppression factor of 5 at pT=7GeV in central vs. peripheral collisions

Spectral ratios increase at higher pT

Wide pT and pseudorapidity coverage of charged particle spectra

Abstract

The measurement of charged particle spectra in heavy ion collisions is a way to study properties of hot and dense matter created in these interactions. The centrality dependence of the spectral shape is an important tool to understand the energy loss mechanism. The ATLAS detector at the LHC accumulated integrated luminosity equal to 0.15nb^{-1} of lead-lead data at 2.76TeV per nucleon-nucleon pair. Due to the excellent capabilities of the ATLAS detector, and its stable operation in 2010 and 2011 heavy ion physics runs, these data allow measurements of the charged particle spectra and their ratios in different centrality bins over a wide range of transverse momenta (0.5-150GeV) and pseudorapidity (|eta|<2.5). The measured ratio central to peripheral events shows a suppresion by a factor of 5 at pT=7GeV. At higher pT the ratio increases.