Influence of Coulomb distortion on polarization observables in elastic electromagnetic lepton hadron scattering at low energies

Polarization observables in elastic electromagnetic hadron-lepton scattering at low energies are studied, with special emphasis on the influence of Coulomb distortion. The spin-dependent contributions to the scattering matrix, i.e., the hyperfine and spin-orbit interactions of leptons and hadrons, are calculated in a distorted-wave Born approximation based on nonrelativistic Coulomb wave functions. For like charges the Coulomb repulsion greatly reduces the size of polarization observables compared to the plane-wave Born approximation, whereas for opposite charges the Coulomb attraction leads to a substantial increase in these observables for hadron laboratory kinetic energies below about 20 keV.