
We study the mass, width and couplings of the lightest resonance multiplet with I(J(PC)) = 1(1()) quantum numbers. Effective field theories based on chiral symmetry are employed in order to describe the form factor associated with the two pseudoscalar matrix element of the QCD vector current. The bare poles of the intermediate resonances are regularized through a DysonSchwingerlike summation. We explore the role of the resonance width in physical observables and make a coupledchannel analysis of the finalstate interactions. This provides many interesting properties, like the pole mass Mrho(pole) = 764.1 +/ 2.7(2.5)(+4.0) MeV. At energies E greater than or similar to 1 GeV, a second 1(1()) resonance multiplet is considered in order to describe the data in a more consistent way. From the phenomenologically extracted resonance couplings, we obtain the chiral coupling L9(r)(mu(0)) = (7.04 +/ 0.05(0.27)(+0.19)) (.) 10(3), at mu(0) = 770 MeV, and show how the running with the scale p affects the resonance parameters. A 1/NC counting is adopted in this work and the consistency of the largeNC expansion is tested. Finally, we make an estimation of the contribution from diagrams with resonances in crossed channels.
