  Momentum-space azimuthal harmonic event planes (EP) are constructed from
final-state midrapidity particles binned in transverse momentum (pT ) in
sqrt(s_NN) = 200 GeV Au+Au collisions in a multi-phase transport (AMPT) model.
The EP correlations between pT bins, corrected by EP resolutions, are smaller
than unity. This indicates that the EP's decorrelate over pT in AMPT,
qualitatively consistent with data and hydrodynamic calculations. It is further
found that the EP correlations approximately factorize into single pT-bin EP
correlations to a common plane. This common plane appears to be the
momentum-space EP integrated over all pT, not the configuration space
participant plane (PP).
