The A5 and the pion field

In this talk, an SU(Nf)×SU(Nf) Yang-Mills model with a compact extra-dimension is used to describe the spin-1 mesons and pions of massless QCD in the large-Nc. The right 4D symmetry and symmetry-breaking pattern is produced by imposing appropriate boundary conditions. The Goldstone boson (GB) fields are constructed using a Wilson line. We derive the low-energy limit (chiral lagrangian), discuss ρ-meson dominance, sum rules between resonance couplings and the relation with the QCD high-energy behavior. Finally, we provide an analytic expression for the two-point function of vector and axial currents.