Recherche de particules supersymetriques se desintegrant avec violation du nombre baryonique dans les collisions e+e- produites dans le detecteur L3 a LEP

摘要

This thesis is based on baryon number and then R-Parity (Rp) violation, both allowedin the Minimal Supersymmetric Standard Model (MSSM) framework.This hypothesis leads to supersymmetric particles' decay topologies significantly differentfrom those ever studied and opens new possibilities on searches for supersymmetry.We will detail throughout this work the phenomenological consequences of the baryonnumber violation hypothesis, the resulting decay signatures in an e+e- collider andthe analysis setup developped to isolate these decays in the data collected by the L3experiment at LEP between 1997 and 2000.In order to validate the search methods developped, we also measured the cross-sectionof the process e+e- -> ZZ -> q qbar q' q'bar.