Universality of the Holographic Angular Momentum Cutoff

The AdS/CFT dual description of a peripheral heavy ion collision involves an asymptotically AdS rotating black hole. The explicitly known black holes of this kind, with planar event horizon topology [the "KMV$_0$" spacetimes], have been shown to be unstable when string-theoretic effects are taken into account. It has been argued that this implies a "holographic" angular momentum cutoff for peripheral collisions at very high energies. However, the KMV$_0$ black hole corresponds to a specific velocity distribution in the aftermath of a peripheral collision, and this distribution is not realistic at all points of the interaction zone. It could therefore be argued that the angular momentum cutoff is an artefact of this particular choice of bulk geometry. We demonstrate that, on the contrary, a Quark-Gluon Plasma with any physically reasonable internal velocity distribution corresponds to a black hole which is still unstable, in the same way as the KMV$_0$ spacetime. The angular momentum cutoff is therefore a universal prediction of the holographic description of these collisions.