Entropy production in collisions of gravitational shock waves and of heavy ions

We calculate the area of a marginally trapped surface formed by a head-on collision of gravitational shock waves in AdSD. We use this to obtain a lower bound on the entropy produced after the collision. A comparison to entropy production in heavy-ion collisions is included. We also discuss an O(D-2) remnant of conformal symmetry, which is present in a class of gravitational shockwave collisions in AdSD and which might be approximately realized (with $D=5$) in central heavy-ion collisions.