Measurement of Dijets with a Leading Neutron in ep Interactions at HERA

Measurements are reported of the production of dijet events with a leading neutron in ep interactions at HERA. Differential cross sections for photoproduction and DIS are presented. LO QCD simulation programs and NLO perturbative QCD calculations are compared with the measurements. Models in which the real or virtual photon interacts with a parton of an exchanged pion are found to be in good agreement with the measured cross sections. The fraction of leading neutron dijet events with respect to all dijet events is also determined.