Search for Particles and Forces Beyond the Standard Model at HERA ep and Tevatron pp̄ Colliders ∗

A review of searches for physics beyond the Standard Model carried out at high energy leptonhadron and hadron-hadron facilities is presented, with emphasis on topics of interest for future data taking at the upgraded Tevatron pp̄ and HERA ep colliders. The status and discovery prospects are discussed for leptoquarks, Technicolour and supersymmetry, forbidden lepton and quark flavourchanging processes, extra gauge bosons, excited states of composite fermions, generic contact interactions and extra compactified dimensions. ∗submitted for publication in “Progress in Particle and Nuclear Physics” under the title: “Search for Particles and Forces Beyond the Standard Model in High Energy Lepton-Hadron and Hadron-Hadron Collisions”