Exotic quark production in ep collisions

We investigate the single production and decay of charge −1/3, weak isosinglet vectorlike exotic D quarks in string inspired E6 theories at future ep colliders; THERA with s=1TeV, L=40pb−1 and CERN Large Hadron Electron Collider (LHeC) with s=1.4TeV, L=104pb−1. We found that an analysis of the decay modes of D should probe the mass ranges of 100-450 GeV and 100-1200 GeV at the center of mass energies, 1 and 1.4 TeV, respectively.