Inelastic diffraction and meson radii

It is shown that meson radii can be extracted from diffractive scattering experiments of the type: m + p → m + X, where p stands for the target proton, and m for the incident charged meson π, π, K, or K. The basis of the method used to perform this extraction is the QCD-based SOC-picture for inelastic diffraction in high-energy hadron-hadron and lepton-hadron collisions proposed in a recent Letter. The obtained results for pion and kaon charge radii are compared with those determined in meson form factor measurements. Ever since it is known that not only nucleons, but also pions and kaons, are spatially extended objects, determination of meson radii has been of considerable interest — both experimentally and theoretically (see e.g. Refs.[1-12] and papers cited therein). Independent of the fact whether the obtained information on meson radii is obtained from electroproduction1–3, from ee-annihilation, or from direct meson-electron scattering6–12 experiments, such information have always been extracted from meson form factors — based on Feynman graphs (or subgraphs) in which the meson is scattered elastically in an electromagnetic field. Can we determine the spatial extension of a meson without any knowledge of its electromagnetic ∗ Present address: Chinese Academy of Sciences, Institute of Theoretical Physics, POB 2735, Beijing 100080, China