A search for excited fermions at HERA

A search for excited fermions f of the first generation in scattering at the collider HERA is presented using H1 data with an integrated luminosity of 37 pb. All electroweak decays of excited fermions, f f f W,f Z are considered and all possible final states resulting from the Z orW hadronic decays or decays into leptons of the first two generations are taken into account. No evidence for f production is found. Mass dependent exclusion limits on cross-sections and on the ratio of coupling constants to the compositeness scale are derived. Received: 19 July 2000 / Published online: 23 October 2000