A light stop and its consequences at the Tevatron and LEP II

An interesting prediction of a string-inspired {\em one-parameter} SU(5)\times U(1) supergravity model, is the fact that the lightest member (\tilde t_1) of the top-squark doublet (\tilde t_1,\tilde t_2), may be substantially lighter than the top quark. This sparticle (\tilde t_1) may be readily pair-produced at the Tevatron and, if m_{\tilde t_1}\lsim130\GeV, even be observed at the end of Run IB. Top-squark production may also be an important source of sought-for top-quark signatures in the dilepton and \ell+jets channels. Therefore, a re-analysis of the top data sample in the presence of a possibly light top-squark appears necessary before definitive statements concerning the discovery of the top quark can be made. Such a light top-squark is linked with a light supersymmetric spectrum which can certainly be searched for at the Tevatron through trilepton and squark-gluino searches, and at LEPII through direct \tilde t_1 pair-production (for m_{\tilde t_1}\lsim100\GeV) and via chargino and Higgs-boson searches.