Event-plane decorrelation over pseudo-rapidity and its effect on   azimuthal anisotropy measurement in relativistic heavy-ion collisions
  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. 
Kai Xiao, Feng Liu, and Fuqiang Wang
nucl-th hep-ph nucl-ex