  At strong coupling holographic studies have shown that heavy ion collisions
do not obey normal boost invariance. Here we study a modified boost invariance
through a complex shift in time, and show that this leads to surprisingly good
agreement with numerical holographic computations. When including perturbations
the agreement becomes even better, both in the hydrodynamic and the
far-from-equilibrium regime. One of the main advantages is an analytic
formulation of the stress-energy tensor of the longitudinal dynamics of
holographic heavy ion collisions.
