Correlations between the deconfining and chiral transitions in holographic QCD

TL;DR

This paper uses an improved holographic QCD model to explore the relationship between deconfining and chiral phase transitions, revealing how the scaling dimension influences transition types and their correlation.

Contribution

It introduces a coupled Einstein-dilaton-scalar model to study the simultaneous deconfining and chiral transitions in holographic QCD, highlighting the role of the scaling dimension of the dual operator.

Findings

The scaling dimension affects chiral transition behavior.

Equation of state matches lattice results for certain parameters.

Transition nature shifts from crossover to first-order with parameter changes.

Abstract

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 $\Delta$ of the dual operator of the dilaton manifest in chiral transitions, although the equation of state can all be matched with the two-flavor lattice results for $\Delta=2.5, 3, 3.5$ in the decoupling case of $\beta=0$. In the weak-coupling case with smaller $\beta$, both the equation of state and the chiral transition exhibit a crossover behavior and turn into first-order phase transitions with the increase of $\beta$.