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

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