Charged Particle Production at Large Transverse Momentum in Pb$-$Pb Collisions at $\sqrt{s_{NN}}=2.76$ TeV Measured with ALICE at the LHC

TL;DR

This paper reports measurements of charged particle spectra at high transverse momentum in Pb-Pb collisions at 2.76 TeV, revealing significant suppression compared to proton-proton collisions, indicating strong medium effects at LHC energies.

Contribution

First measurement of high-$p_{T}$ charged particle suppression in Pb-Pb collisions at 2.76 TeV with detailed $R_{AA}$ analysis showing stronger suppression than at RHIC.

Findings

High-$p_{T}$ particle suppression factor $ oughly 6$ at 6-7 GeV/c

$R_{AA}$ rises to about 0.4 at 50 GeV/c

Suppression stronger than at RHIC energies

Abstract

Transverse momentum ($p_{T}$) spectra of charged particles are measured as a function of event centrality in Pb$-$Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with ALICE at the LHC. The spectra are compared to those measured in pp collisions at the same collision energy in terms of the nuclear modification factor $R_{AA}$. The high-$p_{T}$ charge particle production in central Pb$-$Pb collisions ($0-5%$) is strongly suppressed by a factor $\approx6$ at transverse momenta $p_{T}=6-7$ GeV/c as compared to expectation from independent superposition of nucleon-nucleon collisions. Above $p_{T}=7$ GeV/c there is a significant rise in the nuclear modification factor, which reaches $R_{AA} \approx 0.4$ at $p_{T}=50$ GeV/c. The measured suppression of high-$p_{T}$ particles is stronger than that measured at RHIC.