Deep-Inelastic Electroproduction of Neutrons in the Proton Fragmentation   Region
  Experiments at HERA looking for deep-inelastic electroproduction of neutrons in the proton fragmentation region are in progress. They are aimed to measure the pion structure function at small Bjorken $x$. The important condition for such a study is to establish under what kinematical conditions the dominance of the pion-pole graph in the process is guaranteed. We analyse other sources of theleading neutron, in order to figure out the kinematical region where the one-pion exchange dominates. 
B.Z. Kopeliovich, B. Povh (Heidelberg), I.K. Potashnikova (Dubna)