Théorie et Phénoménologie du MSSM avec des Scalaires Lourds

We perform a comprehensive analysis of the Minimal Supersymmetric Standard Model in the scenario where the scalar partners of the fermions and the Higgs particles (except for the Standard-Model-like one) are assumed to be very heavy and are removed from the low-energy spectrum. We first summarize our determination of the mass spectrum, in which we include the one-loop radiative corrections and resum to all orders the leading logarithms of the large scalar masses. We then study in detail the phenomenology of the model in scenarios where the gaugino mass parameters are non-universal at the GUT scale. We discuss the constraints from collider searches and high-precision measurements, the cosmological constraints on the relic abundance of the neutralino candidate for the Dark Matter in the Universe and the gluino lifetime. We then analyze the decays of the Higgs boson, of charginos and neutralinos and of gluinos, and highlight the differences from the case of universal gaugino masses. In a second part, we analyse the prospects to reconstruct at high-energy colliders the basic parameters of the MSSM with heavy scalars. We discuss at which extent the charginos and neutralinos can be produced and the low-energy Lagrangian parameters which enter the various measurables can be precisely measured. Using the high-precision measurements, we determine the parameters of the model both at the low and high-energy scales. It is shown that model parameters can be reconstructed even in the general case where the soft-SUSY breaking gaugino mass parameters are non universal at the high scale. Finally, we study the possibility of identifying dark matter properties from XENON-like 100 kg experiments and the GLAST satellite mission. We show that whereas direct detection experiments will probe efficiently light WIMPs, given a positive detection, GLAST will be able to confirm and even increase the precision in the case of a NFW profile. We also predict the rate of production of a WIMP in the next generation of colliders (ILC), and compare their sensitivity to the WIMP mass with the XENON and GLAST projects.