  Peripheral collisions of heavy ions can give rise to extremely intense
magnetic fields. It has been suggested that these fields might invalidate the
holographic description of the corresponding quark-gluon plasmas, assuming that
these can be modelled by strongly coupled field theories. In the case of the
plasmas produced in collisions at the RHIC facility (including in the beam
energy scans), it is known how to deal with this problem: one has to take into
account the large angular momenta generated in these plasmas, and the effects
of the baryonic chemical potential. But this does not work for the plasmas
produced in peripheral collisions at the LHC. However, these results neglect
some (less significant) aspects of bulk physics; could it be that the problem
is resolved by taking into account these lower-order effects? Here we use a
bulk dilatonic field (fully compatible with boundary data, as well as with the
asymptotically AdS character of the bulk geometry) as a model of these effects,
and show that this is unlikely to be the solution. Thus, the existence of a
consistent holographic description of the most extreme LHC plasmas remains open
to question.
