Measurement of elliptic and higher order flow harmonics at $\sqrt{s_{NN}}=2.76$ TeV Pb+Pb collisions with the ATLAS Detector

TL;DR

This paper reports detailed measurements of elliptic and higher order flow harmonics in Pb+Pb collisions at 2.76 TeV using the ATLAS detector, revealing insights into collective flow phenomena and their scaling behaviors.

Contribution

It provides a comprehensive analysis of flow harmonics $v_2$-$v_6$ across various ranges, comparing methods and explaining features like the ridge and mach-cone as collective flow effects.

Findings

Flow harmonics are consistent across methods in certain ranges.

The ridge and mach-cone phenomena are largely explained by collective flow.

Scaling relations in $p_T$ dependence of $v_n$ are observed.

Abstract

The measurements of flow harmonics $v_2$-$v_6$ using the event plane and two particle correlations methods in broad $p_T$, $\eta$ and centrality ranges using the ATLAS detector at LHC are presented. ATLAS recorded about 9 $\mu \textrm{b}^{-1}$ of lead-lead collision data in the 2010 heavy ion run. The full azimuthal acceptance of the ATLAS detector in $\pm2.5$ units of pseudorapidity for charged hadrons and the large amount of data allows for a detailed study of the flow harmonics. The $p_T$, centrality and $\eta$ ranges where the two methods give consistent $v_n$ and where they disagree are discussed. It is shown that the ridge as well as the so called "mach-cone" seen in two particle correlations are largely accounted for by the collective flow. Some scaling relations in the $p_T$ dependence of the $v_n$ are also discussed.