  We consider high energy collisions of two shock waves in AdS_5 as a model of
ultrarelativistic nucleus-nucleus collisions in the boundary theory. We first
calculate the graviton field produced in the collisions in the NLO and NNLO
approximations, corresponding to three- and four-graviton exchanges with the
shock waves. We then consider the asymmetric limit where the energy density in
one shock wave is much higher than in the other one. In the boundary theory
this setup corresponds to proton-nucleus collisions, with the nucleus being the
denser of the two shock waves and the proton being the less dense one.
Employing the eikonal approximation we find the exact high energy analytic
solution for the metric in AdS_5 for the asymmetric collision of two
delta-function shock waves. The solution resums all-order graviton exchanges
with the "nucleus" shock wave and a single-graviton exchange with the "proton"
shock wave. Using the holographic renormalization prescription we read off the
energy-momentum tensor of the matter produced in proton-nucleus collisions. We
show in explicit detail that in the boundary theory the proton is completely
stopped by strong-coupling interactions with the nucleus, in agreement with our
earlier results. We also apply the eikonal technique to the asymmetric
collision of two unphysical delta-prime shock waves, which we introduced in an
earlier work as a means of modeling nuclear collisions with weak coupling
initial dynamics. We obtain a surprising result that, for delta-prime shock
waves, the multiple bulk graviton exchange series giving the leading
energy-dependent contribution to the energy-momentum tensor terminates at the
order of two graviton exchanges with the nucleus.
