Búsqueda de charginos con el detector DELPHI de LEP a $E_{cm}=130 - 172 GeV$

The goal of this work is the search for charginos using the data collected with the DELPHI detector at LEP during the years 1995~--~1996 at energies $ E_{cm} =$~130.4, 136.3, 161.4 and 172.4~GeV. In this thesis the methods used and the results obtained are described. This study has been performed within the theoretical framework of the Minimal Standard Supersymmetric Model (MSSM), assuming Grand Unification and $R$--parity conservation. Concerning the nature of the lightest supersymmetric particle, two cases have been treated: the ``NeutraliNO1LSP scenario'' and the ``Gravitino LSP scenario''.