Shocks and sounds in Quark–Gluon Plasma

Large energy deposition from LHC quenching jets restarted interest to shock formation. Shocks also have theoretical significance as the simplest out-of-equilibrium setting without time dependence. While weak shocks have small gradients and can be treated hydrodynamically in the Navier-Stokes (NS) approximation, the ones without a small parameter (strong shocks) needs other methods. Two of those will be applied: (i) the “resummed hydrodynamics” proposed earlier by Lublinsky and myself; and (ii) AdS/CFT correspondence, which uses the gravitational setting. In the latter case we apply novel variational approach and find approximate solution. The conclusion from both treatments is that the strong shocks deviate from NS only be few percent. We then propose a novel mechanism of shock production at hadronization, from Raileigh collapse of the QGP bubbles. Further discussion of the “fireball sonograms” deals with shocks/sounds produced by the quenching jets.