Phénoménologie d'annihilation de matière noire et de violation non-minimale de la saveur dans le MSSM

In absence of direct experimental evidence, it is essential to constrain the parameter space of the Minimal Supersymmetric Standard Model (MSSM) both at the Supersymmetry breaking and the electroweak scale. After a brief introduction to Supersymmetry (SUSY), we present an extensive analysis of electroweak, low energy, and cosmological constraints in minimal supergravity (mSUGRA) and gauge-mediated SUSY-breaking (GMSB) scenarios. We include the possibility of non-minimal flavour violation (NMFV) in the squark sector and define ``collider-friendly'' benchmark points based on detailed scans of the parameter space. We then consider neutralino pair annihilation into quark-antiquark pairs that dominates wide ranges of the mSUGRA parameter space. We present the corresponding full one-loop QCD and SUSY-QCD calculation and show numerically that the loop diagrams have an important impact on the annihilation cross section and, in consequence, in the prediction of the dark matter relic density, resulting in a modification of the preferred regions of the parameter space. We finally present analytical expressions and numerical predictions for squark, gaugino, and gravitino production cross sections at the LHC in GMSB with NMFV. We also discuss the phenomenology of flavour mixing and cosmological implications on the gravitino mass within this context.