Rho Meson Properties

Abstract

We study the mass, width and couplings of the lightest vector multiplet. Effective field theories based on chiral symmetry and a 1/N_C 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 regularized through a Dyson-Schwinger-like summation. This procedure provides many interesting properties, as the pole mass M_rho{pole}= 764.1 +- 2.7 (^{+4.0}_{-2.5}) MeV and the chiral coupling L9^r(mu0)= (7.04 +- 0.05 (^{+0.19}_{-0.27}))* 10^{-3}, at mu0=770 MeV. We show how the running affects the resonance parameters and that mu is really unphysical, so saturation occurs at any scale.