Electromagnetic form factor of pion in the field theory inspired   approach
  A new formula for the pion form factor F_pi is proposed which takes into account the pseudoscalar meson loops and the mixing among rho(770), rho(1450), and rho(1700). The expression possesses 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 by the detectors SND, CMD-2, KLOE, and 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, the formula gives F_pi, in agreement with the measurements of the NA7 Collaboration. 
N.N. Achasov, A.A. Kozhevnikov
hep-ph hep-ex nucl-th