Vector meson dominance pion electromagnetic form factor with σ-model loop corrections

Abstract

A model is developed for electromagnetic form factor of the pion. One-loop corrections are included in the linear σ−model. The ρ−meson contribution is added in an extended VMD model. The form factor, calculated without fitting parameters, is in a good agreement with experiment for space-like and time-like photon momenta. Loop corrections to the two-pion hadronic contribution a (had,π) µ to the muon anomalous magnetic moment are calculated. The optimal value of the σ−meson mass appears to be close to the ρ−meson mass.