This paper discusses phenomena close to the critical QCD temperature, using the holographic model. One issue studied is the overcooled high-$T$ phase, in which we calculate quasinormal sound modes. We do not find instabilities associated with other first-order phase transitions, but nevertheless observe drastic changes in sound propagation and dissipation. The rest of the paper considers a cluster of the high-$T$ phase in the UV in coexistence with the low-$T$ phase, in a simplified ansatz in which the wall separating them is positioned only in the holographic coordinate. This allows one to find the force on the wall and classical motion of the cluster. When classical motion is forbidden, we evaluate the tunneling probability through the remaining barrier.

• Received 21 September 2013

DOI:https://doi.org/10.1103/PhysRevD.88.105021