UC Santa Cruz

It has been shown through multiple observations that there is approximately five times as much dark matter as normal matter in the universe. Understanding the nature of this dark matter is currently one of the major goals of particle physics. In this dissertation, I examine the relationship between the different ways that dark matter can be detected -- including direct detection, indirect detection in cosmic rays, and direct production at colliders -- and its cosmological properties. In particular, I focus on the relationship between the different detection avenues and two cosmological observables: the thermal relic density of dark matter and cutoff to the matter power spectrum, which corresponds to the smallest dark matter halo that can form in the early universe.

I begin with a relatively model independent study, in which the interactions between dark matter and standard model particles are described by an effective operator. Using constraints from direct detection and collider searches, I come to conclusions about what values are allowed for the matter power spectrum cutoff for each operator. I then turn my attention to particular dark matter candidates: the neutralino and gravitino of supersymmetry and the Kaluza-Klein photon of universal extra dimensions (UED). For these models, I show that there exists a tight correlation between direct detection rates, the flux of neutrinos from dark matter annihilation in the sun, and the matter power spectrum cutoff. I also re-evaluate the relic density for Kaluza-Klein photons in light of the recent measurement of the Higgs boson mass, taking into account previously unconsidered co-annihilation channels. This result is compared against limits on UED from direct detection and collider searches to make statements about the continued viability of the minimal UED model. Finally, I consider how null observations of cosmic anti-deuterons constrain theories of decaying gravitino dark matter that are compatible with the observed relic density.