  The longitudinal long-range correlations of the triangular flow event plane
angles are calculated in a Boltzmann + hydrodynamics hybrid approach. The
potential to disentangle different energy deposition scenarios is explored by
utilizing two different transport approaches for the early non-equilibrium
evolution. In the hadronic transport approach the particle production in high
energy heavy ion reactions is mainly governed by string excitation and
fragmentation processes which are absent in the parton cascade approach. We
find that in both approaches the initial state shows a strong longitudinal
correlation of the event plane angles which is diluted but still persists in
the final state momentum space distributions of the produced particles. A
ridge-like structure can also be caused by near-collinear gluon radiation in a
parton cascade approach and does not necessarily prove longitudinal flux tubes
in the initial state.
