Correlations between the deconfining and chiral transitions in holographic QCD

We consider an improved soft-wall AdS/QCD model coupled to an Einstein-dilaton system, which offers a way to study the deconfining and chiral transitions simultaneously. The correlation between these two transitions has been investigated in detail in the Einstein-dilaton-scalar system with the bulk scalar field representing the vacuum of matters in the flavor sector of the model. We find that the effects of the scaling dimension Δ of the dual operator of the dilaton manifest in chiral transitions, although the equations of state can all be matched with the two-flavor lattice results for Δ =2.5 ,3 ,3.5 in the decoupling case of β =0 . In the weak-coupling case with smaller β , both the equation of state and the chiral transition exhibit a crossover behavior and turn into first-order phase transitions with the increase of β .