Pion Compton Scattering,e+e−Annihilation into Hadrons, and Electromagnetic Form Factors

A model of pion Compton scattering is formulated on the basis of Regge poles and scale invariance. The structure functions for $e^{+}+e^{-}\to {\pi }^{\pm }+\mathrm{hadrons}$ are derived from those for electroproduction by using crossing symmetry, and the cross section for $e^{+}{e}^{-}$ annihilation is calculated by assuming factorization of the Regge residues. The predicted cross section is consistent with recent storage-ring experimental results. The proton and pion electromagnetic form factors are then calculated from finite-energy sum rules and good agreement with the data is obtained. It is found that the $e^{+}{e}^{-}$ annihilation cross section is not inconsistent with a pion form factor which decreases rapidly with increasing momentum transfer squared.