Bubble wall velocity at strong coupling
Francesco Bigazzi, Alessio Caddeo, Tommaso Canneti, Aldo L. Cotrone
Abstract
A bstract 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 $$ Dq\hbox{-} \overline{D}q $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Dq</mml:mi> <mml:mo>‐</mml:mo> <mml:mover> <mml:mi>D</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>q</mml:mi> </mml:math> flavor branes probing the black hole background sourced by a stack of N Dp -branes. We first consider the Witten-Sakai-Sugimoto $$ D4\hbox{-} D8\hbox{-} \overline{D}8 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>D</mml:mi> <mml:mn>4</mml:mn> <mml:mo>‐</mml:mo> <mml:mi>D</mml:mi> <mml:mn>8</mml:mn> <mml:mo>‐</mml:mo> <mml:mover> <mml:mi>D</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mn>8</mml:mn> </mml:math> 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.