Bubble Wall Velocity at Strong Coupling

Using the holographic correspondence as a tool, we determine the steady-state velocity of expanding vacuum bubbles nucleated within chiral finite temperature first-order phase transitions occurring in strongly-coupled large \(N\) QCD-like models. We provide general formulae for the friction force exerted by the plasma on the bubbles and for the steady-state velocity. In the top-down holographic description, the phase transitions are related to changes in the embedding of \(Dq\)-\({\bar Dq}\) flavor branes probing the black hole background sourced by a stack of \(N\) \(Dp\)-branes. We first consider the Witten-Sakai-Sugimoto \(D4\)-\(D8\)-\(\bar D8\) setup, compute the friction force and deduce the equilibrium velocity. Then we extend our analysis to more general setups and to different dimensions. Finally, we briefly compare our results, obtained within a fully non-perturbative framework, to other estimates of the bubble velocity in the literature.