1303.6929 (Danning Li et al.)

Dynamical holographic QCD model for glueball and light meson spectra    [PDF]

Danning Li, Mei Huang

In this work, we offer a systematic framework to describe the gluodynamics and chiral dynamics.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. The dimension-2 dilaton background field $\Phi$ takes the same form as that in the soft-wall model and its square $\Phi^2$ can be identified as the dual field to the gauge invariant operator of the dimension-4 gluon condensate. The gluon condensate in the QCD vacuum breaks conformality and induces a deformed warp factor. Without introducing extra parameters but just 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 gluon condensate 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.

View original: http://arxiv.org/abs/1303.6929