Ricerca di chargini a 130 GeV < $\sqrt{s}$ < 161 GeV, con l'esperimento L3 al LEP

The subject of this work is the search for charginos with the L3 detector at LEP, using the data collected by L3 during the years 1995-1996 at center of mass energies $130 GeV < \sqrt{s} < 161 GeV$. In the thesis are described the design and realization of a new Monte Carlo generator (DFGT) for chargiNO1production and decay at $e^+e^-$ colliders, which is based on the evaluation of the full matrix elements of the process, and the realization and the results of two analysis, one cuts based conventional analysis, and a new and more advanced one based on the EPDE multivariate method. The results of this search are also compared with the predictions of the CMSSM model to obtain esclusion limits on the model parameters space and mass limits on charginos.