Chiral symmetry breaking from five-dimensional spaces

Abstract

Based on the AdS/CFT correspondence we study the breaking of the chiral symmetry in QCD using a simple five dimensional model. The model gives definite predictions for the spectrum of vector mesons, their decay constants and interactions as a function of one parameter related to the quark condensate. We calculate the coefficients L i of the low-energy QCD chiral lagrangian, as well as other physical quantities for the pions. All the predictions are shown to be in good agreement with the experimental data. We also show that they are robust under modifications of the 5D metric in the IR, and that some of them arise as a consequence of the higher-dimensional gauge symmetry. For example, at the tree-level, we find M ρ ≃ √ 3 g ρππ F π , F ρ ≃ √ 3 F π and BR(a 1 → πγ) = 0.

Holographic model for hadrons in deformed AdS5 background

“…Actually this is approximated as v(z) ∼ m q z + cz 3 near z = 0, which reproduces the results of [9,10]. We notice that v(z) includes the parameter λ which is specific to our model as well as m q and c. In other words, the gauge theory considered here is characterized by these three parameters.…”

“…The holographic models of Refs. [9,10,11,12] have essentially the same problem. This is an important problem to be solved in future.…”

Baryon physics in holographic QCD

“…Our list of observables is presented in Table 3; we have taken the physical quantities calculated in this article, together with other mesonic observables calculated in Refs. [8][9][10]18]. Our global fit is carried out by minimizing …”

“…Including the latter could affect strongly the physics of the skyrmion, or even destabilize it. 1 In this article we will consider a very simple five-dimensional model for QCD, which has already been shown to give a quite accurate description of meson physics [8][9][10]. This 5D model has a cutoff scale Λ 5 which is above the lowest-resonance mass m ρ .…”

AdS/QCD phenomenological models from a back-reacted geometry

“…Many efforts have been made in constructing a holographic dual of QCD. See [13,14,15,16,17,18,19,20,21,22,23,24,25,26] and references therein for various approaches. Usually in these models, the background manifold is chosen to be AdS, which means one did not consider the effects of the condensates.…”