GRAPE-Dilepton (version1.1), A Generator for Dilepton Production in ep   Collisions
  GRAPE-Dilepton is a Monte Carlo event generator for dilepton production in ep collisions. The cross-section calculation is based on the exact matrix elements in the electroweak theory at tree level. The dilepton productions via $\gamma \gamma$, $\gamma Z^0$, $Z^0 Z^0$ collisions and via photon internal conversion are taken into account. In addition, the effects of the $Z^0$ on/off-shell production are also included. The relevant Feynman amplitudes are generated by the automatic calculation system GRACE. The calculation of the proton vertex covers the whole kinematical region. This generator has an interface to PYTHIA and SOPHIA to obtain complete hadronic final states. 
Tetsuo Abe