Étude de systèmes dibaryoniques étranges dans les réactions K⁻ + d → K⁺ + X⁻, K⁻ + d → π ⁻ + X⁺ et π ⁺ + d → K⁺ + X⁺ entre 0,9 et 1,4 GeV/c

This thesis presents the results of the analysis of the experiment "Dibaryon" (PS159), performed at CERN. This experiment studies the strange dibaryonic systems in the reactions K- + d →K+ + X-, K- + d →π- + X+ et π+ + d → K+ + X+ between. 9 and 1. 4 GeV/c. A dibaryon, with strangeness -2, is searched for in the reaction K- + d → K+ + X-. An upper limit for the production cross section of such a state is established in the range 5 to 40 nb/sr, for a dibaryon mass between 2100 to 2500 MeV/c2. A signal in the mass spectrum of the x+ system, at 2129 MeV/c2, already indicated in the reaction K- + d →π- + X+, is observed in the reaction π+ + d →K + X+. A study of this signal is performed in these two channels at different energies. The triangular diagram model, with an intermediary sigma exchanged, is in good agreement with the variation of the production cross section in the two channels and as a function of the energy.