BOUNDS ON THE MASS OF EXCITED FERMIONS

According to the present limits, it is possible that the mass of the e xcited fermions (M), which arise in composite models of quarks and le ptons, could lay in the range: m(W) < M much less than Lambda, where Lambda denotes the scale of compositeness. For this scenario, the effe ctive Lagrangian approach should be applied to study systematically th e effects of these new fermions. Using this approach, we discuss the v alidity of the limits on M obtained at FNAL from the direct search. W e also derive indirect bounds on M, which are independent of Al from high precision measurements, using three models (sequential, mirror an d homodoublet).