Transversely-intersecting D-branes at finite temperature and chiral phase transition

Abstract

We consider Sakai-Sugimoto like models consisting of Dq-Dp--branes where Nf flavor Dp and -branes transversely intersect Nc color Dq-branes along two (r+1)-dimensional subspaces. For some values of p and q, the theory of intersections dynamically breaks non-Abelian chiral symmetry which is holographically realized as a smooth connection of the flavor branes at some point in the bulk of the geometry created by Nc Dq-branes. We analyze the system at finite temperature and map out different phases of the theory representing chiral symmetry breaking and restoration. For q ⩽ 4 we find that, unlike the zero-temperature case, there exist two branches of smoothly-connected solutions for the flavor branes, one getting very close to the horizon of the background and the other staying farther away from it. At low temperatures, the solution which stays farther away from the horizon determines the vacuum. For background D5 and D6-branes we find that the flavor branes, like the zero temperature case, show subtle behavior whose dual gauge theory interpretation is not clear. We conclude with some comments on how chiral phase transition in these models can be seen from their open string tachyon dynamics.