A Study On Scalar Dark Matter Model

The thesis is aimed to study the simplest scalar dark matter model.The standard model(SM) of particle physics is a theory describing the fundamen-tal particles, as well as the interaction between them. It successfully explains a wide variety of experimental results. But the standard model is not complete, such as it doesn’t contain a good dark matter candidate. This is a typical example of the strong interplay between particle physics, theoretical physics, cosmology and astrophysics. From one side, theoretical particle physics stimulates the formulation of new theories predicting new particles to be dark matter candidates. On the other side, astrophys-ical observation constrain the properties of the particles and the parameters of the new thoeries.The thesis is organised as follows:In the second chapter, we introduce the standard model and thermodynamics in the expanding universe briefly; In third chapter,we discuss the known properties of dark matter and derive the thermal relics of dark matter; In the chapter 4,we study the simplest scalar dark matter model, ie, a real singlet as the dark matter. We calculate the relic density of the dark matter and its direct detection cross section.We find there is only small parameter space left by adding the constraints from the recent dark matter direct detection experiment, such as LUX; In the 5th chapter, we study the two-doublet-higgs-model with a singlet scalar as dark matter.We also find only small parameter space left by adding the constraints from the recent dark matter direct detection experiment. In the last chapter, it concludes the thesis.