Event-plane decorrelation over pseudo-rapidity and its effect on azimuthal anisotropy measurement in relativistic heavy-ion collisions

TL;DR

This study uses a multi-phase transport model to analyze how event-plane decorrelation over pseudorapidity affects azimuthal anisotropy measurements in relativistic heavy-ion collisions, raising questions about current flow measurement methods.

Contribution

It reveals the extent of event-plane decorrelation over pseudorapidity and its impact on flow measurements, highlighting potential issues in current analysis techniques.

Findings

Event-plane decorrelation increases with pseudorapidity gap.

Third harmonic event planes are anticorrelated between forward and backward rapidities.

Decorrelation may challenge the validity of flow measurements using pseudorapidity gaps.

Abstract

Within A Multi-Phase Transport model, we investigate decorrelation of event planes over pseudorapidity and its effect on azimuthal anisotropy measurements in relativistic heavy-ion collisions. The decorrelation increases with increasing {\eta} gap between particles used to reconstruct the event planes. The third harmonic event planes are found even anticorrelated between forward and backward rapidities, the source of which may root in the opposite orientation of the collision geometry triangularities. The decorrelation may call into question the anisotropic flow measurements with pseudorapidity gap designed to reduce nonflow contributions, hence the hydrodynamic properties of the quark-gluon plasma extracted from those measurements.