A holographic model of deconfinement and chiral symmetry restoration

We analyze the finite temperature behavior of the Sakai-Sugimoto model, which is a holographic dual of a theory which spontaneously breaks a U(Nf)L × U(Nf)R chiral flavor symmetry at zero temperature. The theory involved is a 4 + 1 dimensional supersymmetric SU(Nc) gauge theory compactified on a circle of radius R with anti-periodic boundary conditions for fermions, coupled to Nf left-handed quarks and Nf right-handed quarks which are localized at different points on the compact circle (separated by a distance L). In the supergravity limit which we analyze (corresponding in particular to the large Nc limit of the gauge theory), the theory undergoes a deconfinement phase transition at a temperature Td = 1/2πR. For quark separations obeying L > Lc ≃ 0.97 ∗ R the chiral symmetry is restored at this temperature, but for L < Lc ≃ 0.97 ∗ R there is an intermediate phase which is deconfined with broken chiral symmetry, and the chiral symmetry is restored at TχSB ≃ 0.154/L. All of these phase transitions are of first order.