Target normal spin asymmetry and charge asymmetry for $e\mu$ elastic   scattering and the crossed processes
  Two kinds of asymmetry arise from the interference of the Born amplitude and the box-type amplitude corresponding to two virtual photons exchange, namely charge-odd and one spin asymmetries. In case of unpolarized particles the charge-odd correlation is calculated. It can be measured in combination of electron muon and positron muon scattering experiments. The forward-backward asymmetry is the corresponding quantity which can be measured for the crossed processes. In the case of polarized muon the one-spin asymmetry for annihilation and scattering channels has been calculated. The additional structure function arising from the interference is shown to suffer from infrared divergencies. The background due to electroweak interaction is discussed. 
E. A. Kuraev, V. V. Bytev, Yu. M. Bystritskiy, E. Tomasi-Gustafsson