We show how to incorporate chiral-symmetry breaking in the soft-wall version of the anti-de Sitter/ QCD model by using a modified dilaton profile and a quartic term in the bulk scalar potential. This allows one to separate the dependence on spontaneous and explicit chiral-symmetry breaking. Moreover, our 5D model automatically incorporates linear trajectories and non chiral-symmetry restoration for highly excited radial states. We compare our resulting mass spectra in the scalar, vector, and axial-vector sectors with the respective QCD resonances and find reasonable agreement using the known values for the pion mass and decay constant.

The Anti-de Sitter Space/Conformal Field Theory (AdS/CFT) correspondence may offer new and useful insights into the non-perturbative regime of strongly coupled gauge theories such as Quantum Chromodynamics (QCD). Recently a modified soft-wall AdS/QCD model incorporated independent sources for explicit and spontaneous chiral symmetry breaking and linear confinement. This model contains a modified dilaton and higher-order interaction terms in the Lagrangian. Within this model we explore the radial pseudoscalar mass spectrum using two different representations of the pion field. We find the mass eigenvalues associated with each representation, show the equivalence between the two, and find good agreement with the pion masses. The Gell-Mann-Oakes-Renner relation is naturally obtained.

We incorporate chiral symmetry breaking in a soft-wall version of the AdS/QCD model by using a modified dilaton profile and a quartic term in the bulk scalar potential. This allows one to separate the dependence on spontaneous and explicit chiral symmetry breaking. The resulting mass spectra in the scalar, vector and axial-vector sectors compares favorably with the respective QCD resonances.

We propose a finite-temperature holographic model with a soft-wall geometry that incorporates two scalar fields, dual to the gluon and chiral operators. A series solution is presented as the dynamical, black-hole solution to Einstein's equations. We use the solution to calculate the thermal properties of the corresponding 4D gauge theory. Gluon and chiral thermal condensates contribute leading-order terms that affect the speed of sound through and entropy of the 4D thermal medium. At a temperature T c ∼ 900 MeV, we find a phase transition, which is much higher than lattice QCD calculations. However, the transition only exists with nonzero thermal condensates.

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