Seminarium "Teoria cząstek elementarnych i kosmologia"

In the view of strong constraints from dark matter (DM) direct and indirect searches on the conventional self-interacting DM model in which the DM is generated by the freeze-out mechanism, we study a vector DM (VDM) model in which the VDM can be produced by the freeze-in mechanism through the Higgs portal to the Standard Model sector. It turns out that the electroweak phase transition have a substantial impact on the prediction of the VDM relic density. We further assume that the dark Higgs boson which gives the VDM mass is so light that it can induce strong VDM self-interactions and solve the small-scale structure problems of the Universe. As illustrated by the latest LUX data, the extreme smallness of the Higgs portal coupling required by the freeze-in mechanism implies that the dark matter direct detection bounds are easily satisfied. However, the model is well constrained by the DM indirect detection data from BBN, CMB, AMS-02, and diffuse γ/X-rays. Consequently, only when the dark Higgs mass is at most of O(keV) does there exist a parameter region which leads to a correct amount of VDM relic abundance and an appropriate VDM self-scattering while satisfying all other constraints simultaneously.