Elliptic flow at high transverse momentum in Pb-Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV with the ALICE experiment

TL;DR

This paper measures the elliptic flow coefficient $v_2$ for charged particles in Pb-Pb collisions at 2.76 TeV, revealing a finite, positive $v_2$ at high transverse momentum, which helps understand parton energy loss mechanisms.

Contribution

It provides detailed $v_2$ measurements up to 20 GeV/c at LHC energies, extending previous lower-energy results and offering new insights into particle behavior at high transverse momentum.

Findings

$v_2$ remains positive and approximately constant above 8 GeV/c

Proton $v_2$ exceeds pion $v_2$ up to 8 GeV/c

Results are compared with lower-energy RHIC data

Abstract

An observable that can be used to better constrain the mechanism responsible for the parton energy loss is the elliptic azimuthal event anisotropy, $v_2$. We report on measurements of $v_2$ for inclusive and identified charged particles in Pb-Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV recorded by the ALICE experiment at the LHC. $v_2$ is presented for a wide range of particle transverse momentum up to $p_T=20$ GeV/c. The particle $v_2$ is finite, positive and approximately constant for $p_T>8$ GeV/c. The proton $v_2$ is higher than that of the pion up to about $p_T=8$ GeV/c. The results are compared to the measurements at lower energy reported by RHIC experiments.