Measurement of Event Plane Correlations in Pb-Pb Collisions at $\sqrt{s_{\mathrm{NN}}}$=2.76 TeV with the ATLAS Detector

Abstract

A measurement of correlations between event-plane angles ${\Phi }_n$ is presented as a function of centrality for Pb-Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV. These correlations are estimated from observed event-plane angles ${\Psi }_n$ obtained from charged particle or transverse energy flow measured over a large pseudorapidity range $|\eta |<4.8$, followed by a resolution correction that accounts for the dispersion of ${\Psi }_n$ relative to ${\Phi }_n$. Various correlators involving two or three event planes with acceptable resolution are measured. Significant positive correlations are observed for $4({\Phi }_2-{\Phi }_4)$, $6({\Phi }_2-{\Phi }_6)$, $6({\Phi }_3-{\Phi }_6)$, $2{\Phi }_2+3{\Phi }_3-5{\Phi }_5$, $2{\Phi }_2+4{\Phi }_4-6{\Phi }_6$ and $-10{\Phi }_2+4{\Phi }_4+6{\Phi }_6$. However, the measured correlations for $2{\Phi }_2-6{\Phi }_3+4{\Phi }_4$ are negative. These results may shed light on the patterns of the fluctuation of the created matter in the initial state as well as the subsequent hydrodynamic evolution.

Comments: 5 pages, 4 figures. Proceedings for Hard Probes 2012, Cagliari, Italy