Rho meson properties

We study the mass, width and couplings of the lightest vector multiplet. Effective field theories based on chiral symmetry and a 1/NC counting are adopted in order to describe the vector form factor associated to the two-pseudoscalar matrix element of the QCD vector current. The bare poles of the intermediate s-channel resonances are regularised through a Dyson-Schwinger-like summation. This procedure provides many interesting properties, as the pole mass Mρpole = 764.1 ± 2.7-2.5+4.0 MeV and the chiral coupling L9τ(μ0) = (7.04 ± 0.05-0.27+0.19) . 10-3, at μ0 = 770 MeV. We show how the running affects the resonance parameters and that μ is really unphysical, so saturation occurs at any scale. This talk is mainly based on Ref. 1