Multiple Parton Interactions in High P_T Hadronic Processes

The thesis is organized as follows: in section II, devoted to the phenomenology of disconnected processes, we review successively the multi-constituent scattering as a model for elastic scattering at wide-angle, the productibn of baryons with large transverse momentum and account at some length for the recent phenomenological development of high P multi-jets, gauge boson pairs etc. produced via the double scattering mechanism. We end up the section with a brief review of the single and double Drell-yan cross sections. Section III deals with the conceptual aspect of the multiparton scattering, where we analayse the double Drell-Yan mechanism in the QCD framework.