New Models of Dark Matter and Prospects for Measurements.

Abstract

This thesis covers a range of topics in model building and measurements with an interest in solving the dark matter problem. We begin with a model where the dark matter properties today are different than they were at the time of its freeze-out. Utilizing measurements of the dark matter mass and couplings, an attempt would be made to reconstruct the history of the Universe. This would lead to incorrect inferences. Our implementation requires a new scalar field which undergoes a phase transition at late times. Next a model of asymmetric dark matter is proposed. By introducing a supersymmetric hidden sector with an abelian gauge boson, we can efficiently annihilate away the symmetric component of the dark matter abundance and generate the mass scale for the dark matter dynamically. The resultant signals for direct detection experiments are explored. In order to explain the excess in positions as seen by the PAMELA experiment, a second model of asymmetric dark matter is put forward. This theory accommodates the large annihilation cross section and leptophilic nature of the final states as required to explain the PAMELA anomaly naturally within this framework. We then move on to discuss the experimental prospects for dark matter measurements. If the dark matter is a WIMP, a correlation should exist between the spin-independent and spin-dependent scattering cross sections. We argue that regardless of whether or not the dark matter is a thermal or non-thermal WIMP, the natural range of direct detection cross sections should be explored by existing or next generation experiments. Another experiment relevant for understanding the properties of the dark matter is the large hadron collider. We explore the possibility of measuring the dark matter mass at this experiment using a recently proposed variation on the MT2 kinematic variable. We show that given 100 fb^(−1), the mass of a 150 GeV dark matter candidate can be determined to O(10%) if the parent particle is 300 GeV and has a production cross section of 100 fb.