Flow-plane decorrelations in heavy-ion collisions with multiple-plane cumulants

Abstract

The azimuthal correlations between local flow planes at different (pseudo)rapidities ($\eta$) may reveal important details of the initial nuclear matter density distributions in heavy-ion collisions. Extensive experimental measurements of a factorization ratio ($r_2$) and its derivative ($F_2$) have shown evidence of the longitudinal flow-plane decorrelation. However, nonflow effects also affect this observable and prevent a quantitative understanding of the phenomenon. In this paper, to distinguish decorrelation and nonflow effects, we propose a new cumulant observable, $T_2$, which largely suppresses nonflow. The technique sensitivity to different initial-state scenarios and nonflow effects are tested with a simple Monte Carlo model, and in the end, the method is applied to events simulated by a multiphase transport model (AMPT) for Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. We also emphasize that a distinct decorrelation signal requires not only the right sign of an observable, but also its proper dependence on the $\eta$-window of the reference flow plane, to be consistent with the pertinent decorrelation picture.

arXiv comment12 pages, 15 figures

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Cited by in corpus (1)

• Symmetry plane correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV