Multi-lepton Production at High Transverse Momentum in ep collisions at HERA

Within the Standard Model (SM) the production of multilepton events in ep collisions is possible mainly through photon-photon interactions, where quasi-real photons radiated from the incident electron and proton interact to produce a pair of leptons γγ → ll [4]. The GRAPE Monte Carlo generator [5] interfaced to full detector simulation has been used to simulate multilepton production. This generator is based on the full electro-weak matrix element calculation at tree level. The scattered proton or its remnants is treated in three phase space regions: elastic, quasielastic and inelastic. The main experimental backgrounds to multielectron production are processes where, in addition to a true electron, one or more fake electrons may be reconstructed from the final state particles. The dominant contribution is expected from Neutral Current Deep Inelastic Scattering (NCDIS) where a fake electron from the hadrons or a radiated photon is selected together with the scattered electron. Elastic Compton scattering can also contribute if the high PT photon is misidentified as an electron. Background for multi-muon events are processes where fake muons are reconstructed from isolated hadrons. This contribution is negligible.