Dynamical holographic QCD model for glueball and light meson spectra

TL;DR

This paper develops a dynamical holographic QCD model that accurately describes glueball and light meson spectra by incorporating gluodynamics and chiral dynamics within a unified framework, matching lattice data and revealing key non-perturbative effects.

Contribution

It introduces a self-consistent dynamical holographic QCD model for both pure gluon and two-flavor systems, capturing non-perturbative gluodynamics and chiral symmetry breaking effects.

Findings

Scalar glueball spectra agree with lattice data

Chiral condensate and gluon condensate mixing is crucial for light meson spectra

Negative quadratic dilaton background is disfavored in the model

Abstract

In this work, we offer a dynamical soft-wall model to describe the gluodynamics and chiral dynamics in one systematical framework. We firstly construct a quenched dynamical holographic QCD (hQCD) model in the graviton-dilaton framework for the pure gluon system, then develop a dynamical hQCD model for the two flavor system in the graviton-dilaton-scalar framework by adding light flavors on the gluodynamical background. For two forms of dilaton background field $\Phi=\mu_G^2z^2$ and $\Phi=\mu_G^2z^2\tanh(\mu_{G^2}^4z^2/\mu_G^2)$, the quadratic correction to dilaton background field at infrared encodes important non-perturbative gluodynamics and naturally induces a deformed warp factor of the metric. By self-consistently solving the deformed metric induced by the dilaton background field, we find that the scalar glueball spectra in the quenched dynamical model is in very well agreement with lattice data. For two flavor system in the graviton-dilaton-scalar framework, the deformed metric is self-consistently solved by considering both the chiral condensate and nonperturbative gluodynamics in the vacuum, which are responsible for the chiral symmetry breaking and linear confinement, respectively. It is found that the mixing between the chiral condensate and gluon condensate is important to produce the correct light flavor meson spectra. The pion form factor and the vector couplings are also investigated in the dynamical hQCD model. Besides, we give the criteria for the existence of linear quark potential from the metric structure, and show a negative quadratic dilaton background field is not favored in the graviton-dilaton framework.