Dark matter searches in the context of simplified models

Assuming the validity of General Relativity, a number of puzzling astronomical observations could find an explanation by introducing dark matter. However, such a kind of matter has never been directly observed. From the cosmic microwave background we know that dark matter consists of about 27 % of the energy content of the Universe. Today we rely on ongoing direct and indirect searches as well as collider experiments to detect a particle of dark matter. Numerous extensions of the Standard Model of particle physics contain particle of dark matter. However, the overall diversity and complexity of models would make the characterisation of a possible signal rather difficult and the constraints more model dependent. Therefore, an alternative approach is preferred : the simplified model approach. The present dissertation aims at combining cosmological, astrophysical and collider dark matter searches to set useful constraints on the parameter space of simplified models in order to drive future investigations. This requires accurate computations at collider and the development of new numerical tools to derive constraints from cosmology and astrophysics.(SC - Sciences) -- UCL, 201