Dark Matter at the Fermi Scale

Abstract

Recent breakthroughs in cosmology reveal that a quarter of the Universe is composed of dark matter, but the microscopic identity of dark matter remains a deep mystery. I review recent progress in resolving this puzzle, focusing on two well-motivated classes of dark matter candidates: WIMPs and superWIMPs. These possibilities have similar motivations: they exist in the same well-motivated particle physics models, the observed dark matter relic density emerges naturally, and dark matter particles have mass around 100 GeV, the energy scale identified as interesting over 70 years ago by Fermi. At the same time, they have widely varying implications for direct and indirect dark matter searches, particle colliders, Big Bang nucleosynthesis, the cosmic microwave background, and halo profiles and structure formation. If WIMPs or superWIMPs are a significant component of dark matter, we will soon be entering a golden era in which dark matter will be studied through diverse probes at the interface of particle physics, astroparticle physics, and cosmology. I outline a program of dark matter studies for each of these scenarios, and discuss the prospects for identifying dark matter in the coming years.