Excited-quark and -lepton production at hadron colliders

The existence of excited states is a natural consequence of composite models for quarks and leptons. Production rates and signatures are discussed for hadron colliders presently operating (CERN Super $p\overline{p}$ Synchrotron and Fermilab Tevatron) or under study (CERN Large Hadron Collider and Superconducting Super Collider). Contact interactions may be an important source for excited fermions and could influence the signatures of such particles significantly. Excited quarks could be discovered with masses up to about ⅓-½ of the total collider energy while excited leptons could be accessible up to ⅕-⅓ of the available energy. Large lepton yields are expected if quarks and leptons share common subconstituents.