In this thesis we consider an extension of the Standard Model (SM) with a SU(2) symmetric Dark Sector, and study its viability as a dark matter (DM) model. In the dark sector, a hidden Higgs mechanism generates three massive gauge bosons, which are the DM candidates of the model. We allow a small coupling between the SM Higgs and the scalar of the dark sector, such that there is a scalar mixing.
We study the new interactions in the model and analyse the consequences of the scalar mixing: new possible decays of the Higgs into DM, Higgs decay rates and production cross sections different from SM predictions, and possible interactions between DM and normal matter. We study the evolution of the DM abundance from the early universe to the present and compare the relic densities that the model yields with the experimental value measured by the Planck satellite. We compute the decay rates for the Higgs in the model and test if they are consistent with the experimental data from Atlas, CMS and Tevatron. We calculate the cross section for the interaction between DM and normal matter and compare it with the data from the latest direct detection experiments LUX and XENON100.
We discuss the impact of the experimental constraints on the parameter space of the model, and find the regions that give the best fit to the experimental data. In this work we show that the agreement with the experiments is optimal when both the DM candidates and the dark scalar are heavier than the Higgs boson.
