A journey in dark matter models with non-standard features

In this thesis, we investigate some non-standard aspects of dark matter in the context of weakly-interacting massive particles. We first study the impact of searches for long-lived particles on dark matter models with two concrete realizations: a simplified model which delivers displaced vertices and an effective one which predicts the existence of bound states similar to R-hadrons. In both cases, we find that non-standard signatures are essential in order to fully exploit the potential of LHC for dark matter searches. We then focus our attention on a non-minimal composite Higgs model which can account for dark matter; the greater complexity of the model with respect to the simplest case allows for thermal production of dark matter with a fine tuning which is significantly lower than in other models. In addition, we find that also non-thermal production is possible.