Acoplanar Di-leptons and Mixed events on the basis of two supergravity model predictions

Purpose of this note is to propose a search for typical signatures produced by charginos, neutralinos and sleptons on the basis of two supergravity model predictions, at the highest e⁺ e^- energy which will be available with LEP-II. The typical signatures are of two main classes: i) «pure leptonic» states; ii) «mixed lepton-jets» states. The «pure leptonic» states consist of acoplanar di-leptons with «leading» and «non-leading» leptonic components plus multi-di-lepton states. All with at least two missing momenta. The «mixed lepton-jets» states contain at least two jets and one or three leptons plus missing momenta. All these final states represent clear signatures for SUSY. Cross-sections and branching ratios are computed using two «local» supersymmetry models:i.e. the minimal SU(5) supergravity and the SU(5)×U(1) supergravity. The corresponding numbers of «pure leptonic» and of «mixed lepton-jets» final states are computed. We also discuss the upgrading needed in an experimental set-up at LEP-II especially suited for the detection of the supersymmetry signals expected on the basis of the two supergravity models quoted. These models are at present the most reliable in terms of physically sound assumptions.