Electromagnetic form factor of the pion in the field-theory-inspired approach

A new expression for the pion form factor F-pi is proposed. It takes into account the pseudoscalar meson loops and the mixing of rho(770) with heavier rho(1450) and rho(1700) resonances. The expression has correct analytical properties and can be used in both timelike and spacelike kinematical regions. The comparison is made with the existing experimental data on F-pi, collected with the detectors SND, CMD-2, KLOE, and the BABAR, restricted to energies below 1 GeV. A good description of all four data sets is obtained. In the spacelike region, upon substituting the resonance parameters found in the timelike one, one obtains F-pi, in agreement with the measurements of the NA7 Collaboration.